18 files changed, 185 insertions, 404 deletions

diff --git a/tools/h5diff/h5diff_common.c b/tools/h5diff/h5diff_common.c
index 8e7b181..3403935 100644
--- a/tools/h5diff/h5diff_common.c
+++ b/tools/h5diff/h5diff_common.c
@@ -43,6 +43,7 @@ static struct long_options l_opts[] = {
     { "relative", require_arg, 'p' },
     { "nan", no_arg, 'N' },
     { "compare", no_arg, 'c' },
+    { "use-system-epsilon", no_arg, 'e' },
     { NULL, 0, '\0' }
 };
 
@@ -109,6 +110,11 @@ void parse_command_line(int argc,
                 h5diff_exit(EXIT_FAILURE);
             }
             options->delta = atof( opt_arg );
+            
+            /* -d 0 is the same as default */
+            if (options->delta == 0)
+            options->d=0;
+
             break;
 
         case 'p':
@@ -121,6 +127,11 @@ void parse_command_line(int argc,
                 h5diff_exit(EXIT_FAILURE);
             }
             options->percent = atof( opt_arg );
+
+            /* -p 0 is the same as default */
+            if (options->percent == 0)
+            options->p = 0;
+
             break;
 
         case 'n':
@@ -142,9 +153,16 @@ void parse_command_line(int argc,
         case 'c':
             options->m_list_not_cmp = 1;
             break;
+        case 'e':
+            options->use_system_epsilon = 1;
+            break;
         }
     }
 
+    /* if use system epsilon, unset -p and -d option */
+    if (options->use_system_epsilon)
+        options->d = options->p = 0;
+
     /* check for file names to be processed */
     if (argc <= opt_ind || argv[ opt_ind + 1 ] == NULL)
     {
@@ -277,7 +295,7 @@ check_p_input( const char *str )
         return -1;
 
     x=atof(str);
-    if (x<=0)
+    if (x<0)
         return -1;
 
     return 1;
@@ -311,7 +329,7 @@ check_d_input( const char *str )
         return -1;
 
     x=atof(str);
-    if (x <=0)
+    if (x <0)
         return -1;
 
     return 1;
@@ -344,18 +362,18 @@ void usage(void)
  printf("   -q, --quiet             Quiet mode. Do not do output\n");
  printf("   -c, --compare           List objects that are not comparable\n");
  printf("   -N, --nan               Avoid NaNs detection\n");
-
- printf("   -n C, --count=C         Print differences up to C number\n");
- printf("   -d D, --delta=D         Print difference when greater than limit D\n");
- printf("   -p R, --relative=R      Print difference when greater than relative limit R\n");
-
-
- printf("\n");
-
- printf("  C - is a positive integer\n");
- printf("  D - is a positive number. Compare criteria is |a - b| > D\n");
- printf("  R - is a positive number. Compare criteria is |(b-a)/a| > R\n");
-
+ printf("   -n C, --count=C         Print differences up to C number, C is a positive integer.\n");
+
+ printf("   -d D, --delta=D         Print difference if (|a-b| > D), D is a positive number.\n");
+ printf("   -p R, --relative=R      Print difference if (|(a-b)/b| > R), R is a positive number.\n");
+ printf("   --use-system-epsilon    Print difference if (|a-b| > EPSILON),\n");
+ printf("                           where EPSILON (FLT_EPSILON or FLT_EPSILON) is the system epsilon value. \n");
+ printf("                           If the system epsilon is not defined, use the value below:\n");
+ printf("                               FLT_EPSILON = 1.19209E-07 for float\n");
+ printf("                               DBL_EPSILON = 2.22045E-16 for double\n");
+
+ printf("                           -d, -p, and --use-system-epsilon options are used for comparing floating point values.\n");
+ printf("                           By default, strict equality is used. Use -p or -d to set specific tolerance.\n");  
  printf("\n");
 
  printf(" Modes of output:\n");
diff --git a/tools/h5diff/testfiles/h5diff_10.txt b/tools/h5diff/testfiles/h5diff_10.txt
index 38246d9..4788a79 100644
--- a/tools/h5diff/testfiles/h5diff_10.txt
+++ b/tools/h5diff/testfiles/h5diff_10.txt
@@ -11,13 +11,16 @@ usage: h5diff [OPTIONS] file1 file2 [obj1[obj2]]
    -q, --quiet             Quiet mode. Do not do output
    -c, --compare           List objects that are not comparable
    -N, --nan               Avoid NaNs detection
-   -n C, --count=C         Print differences up to C number
-   -d D, --delta=D         Print difference when greater than limit D
-   -p R, --relative=R      Print difference when greater than relative limit R
-
-  C - is a positive integer
-  D - is a positive number. Compare criteria is |a - b| > D
-  R - is a positive number. Compare criteria is |(b-a)/a| > R
+   -n C, --count=C         Print differences up to C number, C is a positive integer.
+   -d D, --delta=D         Print difference if (|a-b| > D), D is a positive number.
+   -p R, --relative=R      Print difference if (|(a-b)/b| > R), R is a positive number.
+   --use-system-epsilon    Print difference if (|a-b| > EPSILON),
+                           where EPSILON (FLT_EPSILON or FLT_EPSILON) is the system epsilon value. 
+                           If the system epsilon is not defined, use the value below:
+                               FLT_EPSILON = 1.19209E-07 for float
+                               DBL_EPSILON = 2.22045E-16 for double
+                           -d, -p, and --use-system-epsilon options are used for comparing floating point values.
+                           By default, strict equality is used. Use -p or -d to set specific tolerance.
 
  Modes of output:
 
diff --git a/tools/h5diff/testfiles/h5diff_600.txt b/tools/h5diff/testfiles/h5diff_600.txt
index 17af208..82c5240 100644
--- a/tools/h5diff/testfiles/h5diff_600.txt
+++ b/tools/h5diff/testfiles/h5diff_600.txt
@@ -11,13 +11,16 @@ usage: h5diff [OPTIONS] file1 file2 [obj1[obj2]]
    -q, --quiet             Quiet mode. Do not do output
    -c, --compare           List objects that are not comparable
    -N, --nan               Avoid NaNs detection
-   -n C, --count=C         Print differences up to C number
-   -d D, --delta=D         Print difference when greater than limit D
-   -p R, --relative=R      Print difference when greater than relative limit R
-
-  C - is a positive integer
-  D - is a positive number. Compare criteria is |a - b| > D
-  R - is a positive number. Compare criteria is |(b-a)/a| > R
+   -n C, --count=C         Print differences up to C number, C is a positive integer.
+   -d D, --delta=D         Print difference if (|a-b| > D), D is a positive number.
+   -p R, --relative=R      Print difference if (|(a-b)/b| > R), R is a positive number.
+   --use-system-epsilon    Print difference if (|a-b| > EPSILON),
+                           where EPSILON (FLT_EPSILON or FLT_EPSILON) is the system epsilon value. 
+                           If the system epsilon is not defined, use the value below:
+                               FLT_EPSILON = 1.19209E-07 for float
+                               DBL_EPSILON = 2.22045E-16 for double
+                           -d, -p, and --use-system-epsilon options are used for comparing floating point values.
+                           By default, strict equality is used. Use -p or -d to set specific tolerance.
 
  Modes of output:
 
diff --git a/tools/h5diff/testfiles/h5diff_603.txt b/tools/h5diff/testfiles/h5diff_603.txt
index 30fe246..e115114 100644
--- a/tools/h5diff/testfiles/h5diff_603.txt
+++ b/tools/h5diff/testfiles/h5diff_603.txt
@@ -12,13 +12,16 @@ usage: h5diff [OPTIONS] file1 file2 [obj1[obj2]]
    -q, --quiet             Quiet mode. Do not do output
    -c, --compare           List objects that are not comparable
    -N, --nan               Avoid NaNs detection
-   -n C, --count=C         Print differences up to C number
-   -d D, --delta=D         Print difference when greater than limit D
-   -p R, --relative=R      Print difference when greater than relative limit R
-
-  C - is a positive integer
-  D - is a positive number. Compare criteria is |a - b| > D
-  R - is a positive number. Compare criteria is |(b-a)/a| > R
+   -n C, --count=C         Print differences up to C number, C is a positive integer.
+   -d D, --delta=D         Print difference if (|a-b| > D), D is a positive number.
+   -p R, --relative=R      Print difference if (|(a-b)/b| > R), R is a positive number.
+   --use-system-epsilon    Print difference if (|a-b| > EPSILON),
+                           where EPSILON (FLT_EPSILON or FLT_EPSILON) is the system epsilon value. 
+                           If the system epsilon is not defined, use the value below:
+                               FLT_EPSILON = 1.19209E-07 for float
+                               DBL_EPSILON = 2.22045E-16 for double
+                           -d, -p, and --use-system-epsilon options are used for comparing floating point values.
+                           By default, strict equality is used. Use -p or -d to set specific tolerance.
 
  Modes of output:
 
diff --git a/tools/h5diff/testfiles/h5diff_604.txt b/tools/h5diff/testfiles/h5diff_604.txt
index 9357b26..554f2ed 100644
--- a/tools/h5diff/testfiles/h5diff_604.txt
+++ b/tools/h5diff/testfiles/h5diff_604.txt
@@ -1,63 +1,2 @@
-<-d 0> is not a valid option
-usage: h5diff [OPTIONS] file1 file2 [obj1[obj2]] 
-  file1                    File name of the first HDF5 file
-  file2                    File name of the second HDF5 file
-  [obj1]                   Name of an HDF5 object, in absolute path
-  [obj2]                   Name of an HDF5 object, in absolute path
-  OPTIONS
-   -h, --help              Print a usage message and exit
-   -V, --version           Print version number and exit
-   -r, --report            Report mode. Print differences
-   -v, --verbose           Verbose mode. Print differences, list of objects
-   -q, --quiet             Quiet mode. Do not do output
-   -c, --compare           List objects that are not comparable
-   -N, --nan               Avoid NaNs detection
-   -n C, --count=C         Print differences up to C number
-   -d D, --delta=D         Print difference when greater than limit D
-   -p R, --relative=R      Print difference when greater than relative limit R
-
-  C - is a positive integer
-  D - is a positive number. Compare criteria is |a - b| > D
-  R - is a positive number. Compare criteria is |(b-a)/a| > R
-
- Modes of output:
-
-  Default mode: print the number of differences found and where they occured
-  -r Report mode: print the above plus the differences
-  -v Verbose mode: print the above plus a list of objects and warnings
-  -q Quiet mode: do not print output
-
- Compare criteria
-
- If no objects [obj1[obj2]] are specified, h5diff only compares objects
-   with the same absolute path in both files
-
- The compare criteria is:
-   1) datasets: numerical array differences 2) groups: name string difference
-   3) datatypes: the return value of H5Tequal 4) links: name string difference
-   of the linked value
-
- Return exit code:
-
-  1 if differences found, 0 if no differences, 2 if error
-
- Examples of use:
-
- 1) h5diff file1 file2 /g1/dset1 /g1/dset2
-
-    Compares object '/g1/dset1' in file1 with '/g1/dset2' in file2
-
- 2) h5diff file1 file2 /g1/dset1
-
-    Compares object '/g1/dset1' in both files
-
- 3) h5diff file1 file2
-
-    Compares all objects in both files
-
- Note)  file1 and file2 can be the same file. Use
-
-    h5diff file1 file1 /g1/dset1 /g1/dset2
-
-    to compare '/g1/dset1' and '/g1/dset2' in the same file
-
+dataset: </g1/dset3> and </g1/dset4>
+6 differences found
diff --git a/tools/h5diff/testfiles/h5diff_605.txt b/tools/h5diff/testfiles/h5diff_605.txt
index 1c99713..554f2ed 100644
--- a/tools/h5diff/testfiles/h5diff_605.txt
+++ b/tools/h5diff/testfiles/h5diff_605.txt
@@ -1,63 +1,2 @@
-<-d u> is not a valid option
-usage: h5diff [OPTIONS] file1 file2 [obj1[obj2]] 
-  file1                    File name of the first HDF5 file
-  file2                    File name of the second HDF5 file
-  [obj1]                   Name of an HDF5 object, in absolute path
-  [obj2]                   Name of an HDF5 object, in absolute path
-  OPTIONS
-   -h, --help              Print a usage message and exit
-   -V, --version           Print version number and exit
-   -r, --report            Report mode. Print differences
-   -v, --verbose           Verbose mode. Print differences, list of objects
-   -q, --quiet             Quiet mode. Do not do output
-   -c, --compare           List objects that are not comparable
-   -N, --nan               Avoid NaNs detection
-   -n C, --count=C         Print differences up to C number
-   -d D, --delta=D         Print difference when greater than limit D
-   -p R, --relative=R      Print difference when greater than relative limit R
-
-  C - is a positive integer
-  D - is a positive number. Compare criteria is |a - b| > D
-  R - is a positive number. Compare criteria is |(b-a)/a| > R
-
- Modes of output:
-
-  Default mode: print the number of differences found and where they occured
-  -r Report mode: print the above plus the differences
-  -v Verbose mode: print the above plus a list of objects and warnings
-  -q Quiet mode: do not print output
-
- Compare criteria
-
- If no objects [obj1[obj2]] are specified, h5diff only compares objects
-   with the same absolute path in both files
-
- The compare criteria is:
-   1) datasets: numerical array differences 2) groups: name string difference
-   3) datatypes: the return value of H5Tequal 4) links: name string difference
-   of the linked value
-
- Return exit code:
-
-  1 if differences found, 0 if no differences, 2 if error
-
- Examples of use:
-
- 1) h5diff file1 file2 /g1/dset1 /g1/dset2
-
-    Compares object '/g1/dset1' in file1 with '/g1/dset2' in file2
-
- 2) h5diff file1 file2 /g1/dset1
-
-    Compares object '/g1/dset1' in both files
-
- 3) h5diff file1 file2
-
-    Compares all objects in both files
-
- Note)  file1 and file2 can be the same file. Use
-
-    h5diff file1 file1 /g1/dset1 /g1/dset2
-
-    to compare '/g1/dset1' and '/g1/dset2' in the same file
-
+dataset: </g1/dset3> and </g1/dset4>
+6 differences found
diff --git a/tools/h5diff/testfiles/h5diff_606.txt b/tools/h5diff/testfiles/h5diff_606.txt
index 0567106..db361fd 100644
--- a/tools/h5diff/testfiles/h5diff_606.txt
+++ b/tools/h5diff/testfiles/h5diff_606.txt
@@ -12,13 +12,16 @@ usage: h5diff [OPTIONS] file1 file2 [obj1[obj2]]
    -q, --quiet             Quiet mode. Do not do output
    -c, --compare           List objects that are not comparable
    -N, --nan               Avoid NaNs detection
-   -n C, --count=C         Print differences up to C number
-   -d D, --delta=D         Print difference when greater than limit D
-   -p R, --relative=R      Print difference when greater than relative limit R
-
-  C - is a positive integer
-  D - is a positive number. Compare criteria is |a - b| > D
-  R - is a positive number. Compare criteria is |(b-a)/a| > R
+   -n C, --count=C         Print differences up to C number, C is a positive integer.
+   -d D, --delta=D         Print difference if (|a-b| > D), D is a positive number.
+   -p R, --relative=R      Print difference if (|(a-b)/b| > R), R is a positive number.
+   --use-system-epsilon    Print difference if (|a-b| > EPSILON),
+                           where EPSILON (FLT_EPSILON or FLT_EPSILON) is the system epsilon value. 
+                           If the system epsilon is not defined, use the value below:
+                               FLT_EPSILON = 1.19209E-07 for float
+                               DBL_EPSILON = 2.22045E-16 for double
+                           -d, -p, and --use-system-epsilon options are used for comparing floating point values.
+                           By default, strict equality is used. Use -p or -d to set specific tolerance.
 
  Modes of output:
 
diff --git a/tools/h5diff/testfiles/h5diff_612.txt b/tools/h5diff/testfiles/h5diff_612.txt
index 505705b..bbd6b00 100644
--- a/tools/h5diff/testfiles/h5diff_612.txt
+++ b/tools/h5diff/testfiles/h5diff_612.txt
@@ -12,13 +12,16 @@ usage: h5diff [OPTIONS] file1 file2 [obj1[obj2]]
    -q, --quiet             Quiet mode. Do not do output
    -c, --compare           List objects that are not comparable
    -N, --nan               Avoid NaNs detection
-   -n C, --count=C         Print differences up to C number
-   -d D, --delta=D         Print difference when greater than limit D
-   -p R, --relative=R      Print difference when greater than relative limit R
-
-  C - is a positive integer
-  D - is a positive number. Compare criteria is |a - b| > D
-  R - is a positive number. Compare criteria is |(b-a)/a| > R
+   -n C, --count=C         Print differences up to C number, C is a positive integer.
+   -d D, --delta=D         Print difference if (|a-b| > D), D is a positive number.
+   -p R, --relative=R      Print difference if (|(a-b)/b| > R), R is a positive number.
+   --use-system-epsilon    Print difference if (|a-b| > EPSILON),
+                           where EPSILON (FLT_EPSILON or FLT_EPSILON) is the system epsilon value. 
+                           If the system epsilon is not defined, use the value below:
+                               FLT_EPSILON = 1.19209E-07 for float
+                               DBL_EPSILON = 2.22045E-16 for double
+                           -d, -p, and --use-system-epsilon options are used for comparing floating point values.
+                           By default, strict equality is used. Use -p or -d to set specific tolerance.
 
  Modes of output:
 
diff --git a/tools/h5diff/testfiles/h5diff_613.txt b/tools/h5diff/testfiles/h5diff_613.txt
index 1a89746..554f2ed 100644
--- a/tools/h5diff/testfiles/h5diff_613.txt
+++ b/tools/h5diff/testfiles/h5diff_613.txt
@@ -1,63 +1,2 @@
-<-p 0> is not a valid option
-usage: h5diff [OPTIONS] file1 file2 [obj1[obj2]] 
-  file1                    File name of the first HDF5 file
-  file2                    File name of the second HDF5 file
-  [obj1]                   Name of an HDF5 object, in absolute path
-  [obj2]                   Name of an HDF5 object, in absolute path
-  OPTIONS
-   -h, --help              Print a usage message and exit
-   -V, --version           Print version number and exit
-   -r, --report            Report mode. Print differences
-   -v, --verbose           Verbose mode. Print differences, list of objects
-   -q, --quiet             Quiet mode. Do not do output
-   -c, --compare           List objects that are not comparable
-   -N, --nan               Avoid NaNs detection
-   -n C, --count=C         Print differences up to C number
-   -d D, --delta=D         Print difference when greater than limit D
-   -p R, --relative=R      Print difference when greater than relative limit R
-
-  C - is a positive integer
-  D - is a positive number. Compare criteria is |a - b| > D
-  R - is a positive number. Compare criteria is |(b-a)/a| > R
-
- Modes of output:
-
-  Default mode: print the number of differences found and where they occured
-  -r Report mode: print the above plus the differences
-  -v Verbose mode: print the above plus a list of objects and warnings
-  -q Quiet mode: do not print output
-
- Compare criteria
-
- If no objects [obj1[obj2]] are specified, h5diff only compares objects
-   with the same absolute path in both files
-
- The compare criteria is:
-   1) datasets: numerical array differences 2) groups: name string difference
-   3) datatypes: the return value of H5Tequal 4) links: name string difference
-   of the linked value
-
- Return exit code:
-
-  1 if differences found, 0 if no differences, 2 if error
-
- Examples of use:
-
- 1) h5diff file1 file2 /g1/dset1 /g1/dset2
-
-    Compares object '/g1/dset1' in file1 with '/g1/dset2' in file2
-
- 2) h5diff file1 file2 /g1/dset1
-
-    Compares object '/g1/dset1' in both files
-
- 3) h5diff file1 file2
-
-    Compares all objects in both files
-
- Note)  file1 and file2 can be the same file. Use
-
-    h5diff file1 file1 /g1/dset1 /g1/dset2
-
-    to compare '/g1/dset1' and '/g1/dset2' in the same file
-
+dataset: </g1/dset3> and </g1/dset4>
+6 differences found
diff --git a/tools/h5diff/testfiles/h5diff_614.txt b/tools/h5diff/testfiles/h5diff_614.txt
index ec12818..554f2ed 100644
--- a/tools/h5diff/testfiles/h5diff_614.txt
+++ b/tools/h5diff/testfiles/h5diff_614.txt
@@ -1,63 +1,2 @@
-<-p u> is not a valid option
-usage: h5diff [OPTIONS] file1 file2 [obj1[obj2]] 
-  file1                    File name of the first HDF5 file
-  file2                    File name of the second HDF5 file
-  [obj1]                   Name of an HDF5 object, in absolute path
-  [obj2]                   Name of an HDF5 object, in absolute path
-  OPTIONS
-   -h, --help              Print a usage message and exit
-   -V, --version           Print version number and exit
-   -r, --report            Report mode. Print differences
-   -v, --verbose           Verbose mode. Print differences, list of objects
-   -q, --quiet             Quiet mode. Do not do output
-   -c, --compare           List objects that are not comparable
-   -N, --nan               Avoid NaNs detection
-   -n C, --count=C         Print differences up to C number
-   -d D, --delta=D         Print difference when greater than limit D
-   -p R, --relative=R      Print difference when greater than relative limit R
-
-  C - is a positive integer
-  D - is a positive number. Compare criteria is |a - b| > D
-  R - is a positive number. Compare criteria is |(b-a)/a| > R
-
- Modes of output:
-
-  Default mode: print the number of differences found and where they occured
-  -r Report mode: print the above plus the differences
-  -v Verbose mode: print the above plus a list of objects and warnings
-  -q Quiet mode: do not print output
-
- Compare criteria
-
- If no objects [obj1[obj2]] are specified, h5diff only compares objects
-   with the same absolute path in both files
-
- The compare criteria is:
-   1) datasets: numerical array differences 2) groups: name string difference
-   3) datatypes: the return value of H5Tequal 4) links: name string difference
-   of the linked value
-
- Return exit code:
-
-  1 if differences found, 0 if no differences, 2 if error
-
- Examples of use:
-
- 1) h5diff file1 file2 /g1/dset1 /g1/dset2
-
-    Compares object '/g1/dset1' in file1 with '/g1/dset2' in file2
-
- 2) h5diff file1 file2 /g1/dset1
-
-    Compares object '/g1/dset1' in both files
-
- 3) h5diff file1 file2
-
-    Compares all objects in both files
-
- Note)  file1 and file2 can be the same file. Use
-
-    h5diff file1 file1 /g1/dset1 /g1/dset2
-
-    to compare '/g1/dset1' and '/g1/dset2' in the same file
-
+dataset: </g1/dset3> and </g1/dset4>
+6 differences found
diff --git a/tools/h5diff/testfiles/h5diff_615.txt b/tools/h5diff/testfiles/h5diff_615.txt
index 8528c0e..9c8f0c7 100644
--- a/tools/h5diff/testfiles/h5diff_615.txt
+++ b/tools/h5diff/testfiles/h5diff_615.txt
@@ -12,13 +12,16 @@ usage: h5diff [OPTIONS] file1 file2 [obj1[obj2]]
    -q, --quiet             Quiet mode. Do not do output
    -c, --compare           List objects that are not comparable
    -N, --nan               Avoid NaNs detection
-   -n C, --count=C         Print differences up to C number
-   -d D, --delta=D         Print difference when greater than limit D
-   -p R, --relative=R      Print difference when greater than relative limit R
-
-  C - is a positive integer
-  D - is a positive number. Compare criteria is |a - b| > D
-  R - is a positive number. Compare criteria is |(b-a)/a| > R
+   -n C, --count=C         Print differences up to C number, C is a positive integer.
+   -d D, --delta=D         Print difference if (|a-b| > D), D is a positive number.
+   -p R, --relative=R      Print difference if (|(a-b)/b| > R), R is a positive number.
+   --use-system-epsilon    Print difference if (|a-b| > EPSILON),
+                           where EPSILON (FLT_EPSILON or FLT_EPSILON) is the system epsilon value. 
+                           If the system epsilon is not defined, use the value below:
+                               FLT_EPSILON = 1.19209E-07 for float
+                               DBL_EPSILON = 2.22045E-16 for double
+                           -d, -p, and --use-system-epsilon options are used for comparing floating point values.
+                           By default, strict equality is used. Use -p or -d to set specific tolerance.
 
  Modes of output:
 
diff --git a/tools/h5diff/testfiles/h5diff_621.txt b/tools/h5diff/testfiles/h5diff_621.txt
index 96d6c3f..79eebed 100644
--- a/tools/h5diff/testfiles/h5diff_621.txt
+++ b/tools/h5diff/testfiles/h5diff_621.txt
@@ -12,13 +12,16 @@ usage: h5diff [OPTIONS] file1 file2 [obj1[obj2]]
    -q, --quiet             Quiet mode. Do not do output
    -c, --compare           List objects that are not comparable
    -N, --nan               Avoid NaNs detection
-   -n C, --count=C         Print differences up to C number
-   -d D, --delta=D         Print difference when greater than limit D
-   -p R, --relative=R      Print difference when greater than relative limit R
-
-  C - is a positive integer
-  D - is a positive number. Compare criteria is |a - b| > D
-  R - is a positive number. Compare criteria is |(b-a)/a| > R
+   -n C, --count=C         Print differences up to C number, C is a positive integer.
+   -d D, --delta=D         Print difference if (|a-b| > D), D is a positive number.
+   -p R, --relative=R      Print difference if (|(a-b)/b| > R), R is a positive number.
+   --use-system-epsilon    Print difference if (|a-b| > EPSILON),
+                           where EPSILON (FLT_EPSILON or FLT_EPSILON) is the system epsilon value. 
+                           If the system epsilon is not defined, use the value below:
+                               FLT_EPSILON = 1.19209E-07 for float
+                               DBL_EPSILON = 2.22045E-16 for double
+                           -d, -p, and --use-system-epsilon options are used for comparing floating point values.
+                           By default, strict equality is used. Use -p or -d to set specific tolerance.
 
  Modes of output:
 
diff --git a/tools/h5diff/testfiles/h5diff_622.txt b/tools/h5diff/testfiles/h5diff_622.txt
index 9dc3751..09de51d 100644
--- a/tools/h5diff/testfiles/h5diff_622.txt
+++ b/tools/h5diff/testfiles/h5diff_622.txt
@@ -12,13 +12,16 @@ usage: h5diff [OPTIONS] file1 file2 [obj1[obj2]]
    -q, --quiet             Quiet mode. Do not do output
    -c, --compare           List objects that are not comparable
    -N, --nan               Avoid NaNs detection
-   -n C, --count=C         Print differences up to C number
-   -d D, --delta=D         Print difference when greater than limit D
-   -p R, --relative=R      Print difference when greater than relative limit R
-
-  C - is a positive integer
-  D - is a positive number. Compare criteria is |a - b| > D
-  R - is a positive number. Compare criteria is |(b-a)/a| > R
+   -n C, --count=C         Print differences up to C number, C is a positive integer.
+   -d D, --delta=D         Print difference if (|a-b| > D), D is a positive number.
+   -p R, --relative=R      Print difference if (|(a-b)/b| > R), R is a positive number.
+   --use-system-epsilon    Print difference if (|a-b| > EPSILON),
+                           where EPSILON (FLT_EPSILON or FLT_EPSILON) is the system epsilon value. 
+                           If the system epsilon is not defined, use the value below:
+                               FLT_EPSILON = 1.19209E-07 for float
+                               DBL_EPSILON = 2.22045E-16 for double
+                           -d, -p, and --use-system-epsilon options are used for comparing floating point values.
+                           By default, strict equality is used. Use -p or -d to set specific tolerance.
 
  Modes of output:
 
diff --git a/tools/h5diff/testfiles/h5diff_623.txt b/tools/h5diff/testfiles/h5diff_623.txt
index a02f5ea..dc60b94 100644
--- a/tools/h5diff/testfiles/h5diff_623.txt
+++ b/tools/h5diff/testfiles/h5diff_623.txt
@@ -12,13 +12,16 @@ usage: h5diff [OPTIONS] file1 file2 [obj1[obj2]]
    -q, --quiet             Quiet mode. Do not do output
    -c, --compare           List objects that are not comparable
    -N, --nan               Avoid NaNs detection
-   -n C, --count=C         Print differences up to C number
-   -d D, --delta=D         Print difference when greater than limit D
-   -p R, --relative=R      Print difference when greater than relative limit R
-
-  C - is a positive integer
-  D - is a positive number. Compare criteria is |a - b| > D
-  R - is a positive number. Compare criteria is |(b-a)/a| > R
+   -n C, --count=C         Print differences up to C number, C is a positive integer.
+   -d D, --delta=D         Print difference if (|a-b| > D), D is a positive number.
+   -p R, --relative=R      Print difference if (|(a-b)/b| > R), R is a positive number.
+   --use-system-epsilon    Print difference if (|a-b| > EPSILON),
+                           where EPSILON (FLT_EPSILON or FLT_EPSILON) is the system epsilon value. 
+                           If the system epsilon is not defined, use the value below:
+                               FLT_EPSILON = 1.19209E-07 for float
+                               DBL_EPSILON = 2.22045E-16 for double
+                           -d, -p, and --use-system-epsilon options are used for comparing floating point values.
+                           By default, strict equality is used. Use -p or -d to set specific tolerance.
 
  Modes of output:
 
diff --git a/tools/h5diff/testfiles/h5diff_624.txt b/tools/h5diff/testfiles/h5diff_624.txt
index 396a007..016ab77 100644
--- a/tools/h5diff/testfiles/h5diff_624.txt
+++ b/tools/h5diff/testfiles/h5diff_624.txt
@@ -12,13 +12,16 @@ usage: h5diff [OPTIONS] file1 file2 [obj1[obj2]]
    -q, --quiet             Quiet mode. Do not do output
    -c, --compare           List objects that are not comparable
    -N, --nan               Avoid NaNs detection
-   -n C, --count=C         Print differences up to C number
-   -d D, --delta=D         Print difference when greater than limit D
-   -p R, --relative=R      Print difference when greater than relative limit R
-
-  C - is a positive integer
-  D - is a positive number. Compare criteria is |a - b| > D
-  R - is a positive number. Compare criteria is |(b-a)/a| > R
+   -n C, --count=C         Print differences up to C number, C is a positive integer.
+   -d D, --delta=D         Print difference if (|a-b| > D), D is a positive number.
+   -p R, --relative=R      Print difference if (|(a-b)/b| > R), R is a positive number.
+   --use-system-epsilon    Print difference if (|a-b| > EPSILON),
+                           where EPSILON (FLT_EPSILON or FLT_EPSILON) is the system epsilon value. 
+                           If the system epsilon is not defined, use the value below:
+                               FLT_EPSILON = 1.19209E-07 for float
+                               DBL_EPSILON = 2.22045E-16 for double
+                           -d, -p, and --use-system-epsilon options are used for comparing floating point values.
+                           By default, strict equality is used. Use -p or -d to set specific tolerance.
 
  Modes of output:
 
diff --git a/tools/h5diff/testh5diff.sh b/tools/h5diff/testh5diff.sh
index 4167243..b8e743d 100755
--- a/tools/h5diff/testh5diff.sh
+++ b/tools/h5diff/testh5diff.sh
@@ -461,9 +461,9 @@ TOOLTEST h5diff_606.txt -d 0x1 $FILE1 $FILE2 g1/dset3 g1/dset4
 TESTING $H5DIFF -d "1" $SRCFILE1 $SRCFILE2  g1/dset3 g1/dset4
 TOOLTEST h5diff_607.txt -d "1" $FILE1 $FILE2 g1/dset3 g1/dset4
 
-# 6.8: repeated option
-TESTING $H5DIFF -d 1 -d 2 $SRCFILE1 $SRCFILE2   g1/dset3 g1/dset4
-TOOLTEST h5diff_608.txt -d 1 -d 2 $FILE1 $FILE2  g1/dset3 g1/dset4
+# 6.8: use system epsilon 
+TESTING $H5DIFF --use-system-epsilon $SRCFILE1 $SRCFILE2   g1/dset3 g1/dset4
+TOOLTEST h5diff_608.txt --use-system-epsilon $FILE1 $FILE2  g1/dset3 g1/dset4
 
 # 6.9: number larger than biggest difference
 TESTING $H5DIFF -d 200 $SRCFILE1 $SRCFILE2  g1/dset3 g1/dset4
diff --git a/tools/lib/h5diff.h b/tools/lib/h5diff.h
index e0f2ad0..df264dd 100644
--- a/tools/lib/h5diff.h
+++ b/tools/lib/h5diff.h
@@ -25,21 +25,22 @@
  */
 
 typedef struct {
-    int    m_quiet;   /* quiet mide: no output at all */
-    int    m_report;  /* report mode: print the data */
-    int    m_verbose; /* verbose mode: print the data, list of objcets, warnings */
-    int    d;         /* delta, absolute value to compare */
-    double delta;     /* delta value */
-    int    p;         /* relative error to compare*/
-    double percent;   /* relative error value */
-    int    n;         /* count, compare up to count */
-    hsize_t count;    /* count value */
-    int    err_stat;  /* an error ocurred (1, error, 0, no error) */
-    int    cmn_objs;  /* do we have common objects */
-    int    not_cmp;   /* are the objects comparable */
-    int    contents;  /* equal contents */
-    int    do_nans;   /* consider Nans while diffing floats */
-    int    m_list_not_cmp;   /* list not comparable messages */
+    int      m_quiet;               /* quiet mide: no output at all */
+    int      m_report;              /* report mode: print the data */
+    int      m_verbose;             /* verbose mode: print the data, list of objcets, warnings */
+    int      d;                     /* delta, absolute value to compare */
+    double   delta;                 /* delta value */
+    int      p;                     /* relative error to compare*/
+    int      use_system_epsilon;    /* flag to use system epsilon (1 or 0) */
+    double   percent;               /* relative error value */
+    int      n;                     /* count, compare up to count */
+    hsize_t  count;                 /* count value */
+    int      err_stat;              /* an error ocurred (1, error, 0, no error) */
+    int      cmn_objs;              /* do we have common objects */
+    int      not_cmp;               /* are the objects comparable */
+    int      contents;              /* equal contents */
+    int      do_nans;               /* consider Nans while diffing floats */
+    int      m_list_not_cmp;        /* list not comparable messages */
 } diff_opt_t;
 
 
diff --git a/tools/lib/h5diff_array.c b/tools/lib/h5diff_array.c
index 735ea70..77ee74a 100644
--- a/tools/lib/h5diff_array.c
+++ b/tools/lib/h5diff_array.c
@@ -74,9 +74,16 @@
 #define ULLI_FORMAT_P_NOTCOMP "%-15"H5_PRINTF_LL_WIDTH"u %-15"H5_PRINTF_LL_WIDTH"u %-15"H5_PRINTF_LL_WIDTH"d not comparable\n"
 
 
-/* values for FLT_EPSILON same as C Reference manual */
-#define H5DIFF_FLT_EPSILON  .00001
-#define H5DIFF_DBL_EPSILON  .000000001
+/* if system EPSILON is defined, use the system EPSILON; otherwise, use 
+   constants that are close to most EPSILON values */
+
+#ifndef FLT_EPSILON
+#define FLT_EPSILON 1.19209E-07
+#endif
+
+#ifndef DBL_EPSILON
+#define DBL_EPSILON 2.22045E-16
+#endif
 
 
 /*-------------------------------------------------------------------------
@@ -5502,10 +5509,6 @@ error:
 static
 hbool_t equal_double(double value, double expected, diff_opt_t *options)
 {
-    int both_zero;
-    int is_zero;
-
-
     if ( options->do_nans )
     {
         
@@ -5535,22 +5538,15 @@ hbool_t equal_double(double value, double expected, diff_opt_t *options)
         }      
     }
 
-    BOTH_ZERO(value,expected)
-    if (both_zero)
-        return TRUE;
-
-    IS_ZERO(expected)
-    if (is_zero)
-        return(equal_double(expected,value,options));
-
     if (value == expected)
         return TRUE;
 
-    if ( ABS( (value-expected) / expected) < H5DIFF_DBL_EPSILON)
-        return TRUE;
-    else
-        return FALSE;
+    if (options->use_system_epsilon) {
+        if ( ABS( (value-expected) ) < DBL_EPSILON)
+            return TRUE;
+    }
 
+    return FALSE;
 }
 
 /*-------------------------------------------------------------------------
@@ -5566,10 +5562,6 @@ hbool_t equal_double(double value, double expected, diff_opt_t *options)
 static
 hbool_t equal_ldouble(long double value, long double expected, diff_opt_t *options)
 {
-    int both_zero;
-    int is_zero;
-
-    
     if ( options->do_nans )
     {
         
@@ -5599,22 +5591,15 @@ hbool_t equal_ldouble(long double value, long double expected, diff_opt_t *optio
         }       
     }
 
-    BOTH_ZERO(value,expected)
-    if (both_zero)
-        return TRUE;
-
-    IS_ZERO(expected)
-    if (is_zero)
-        return(equal_ldouble(expected,value,options));
-
     if (value == expected)
         return TRUE;
 
-    if ( ABS( (value-expected) / expected) < H5DIFF_DBL_EPSILON)
-        return TRUE;
-    else
-        return FALSE;
+    if (options->use_system_epsilon) {
+        if ( ABS( (value-expected) / expected) < DBL_EPSILON)
+            return TRUE;
+    }
 
+    return FALSE;
 }
 
 #endif /* #if H5_SIZEOF_LONG_DOUBLE !=0 */
@@ -5634,9 +5619,6 @@ hbool_t equal_ldouble(long double value, long double expected, diff_opt_t *optio
 static
 hbool_t equal_float(float value, float expected, diff_opt_t *options)
 {
-    int both_zero;
-    int is_zero;
-
     if ( options->do_nans )
     {
         
@@ -5666,21 +5648,15 @@ hbool_t equal_float(float value, float expected, diff_opt_t *options)
         }       
     }
 
-    BOTH_ZERO(value,expected)
-    if (both_zero)
-        return TRUE;
-
-    IS_ZERO(expected)
-    if (is_zero)
-        return(equal_float(expected,value,options));
-
     if (value == expected)
         return TRUE;
 
-    if ( ABS( (value-expected) / expected) < H5DIFF_FLT_EPSILON)
-        return TRUE;
-    else
-        return FALSE;
+    if (options->use_system_epsilon) {
+        if ( ABS( (value-expected) / expected) < FLT_EPSILON)
+            return TRUE;
+    }
+
+    return FALSE;
 
 }