Merge topic 'tutorial_genExp_rearrange'

ccba87b05b Tutorial: Move step 10 to step 4

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: buildbot <buildbot@kitware.com>
Merge-request: !7506

1 files changed, 8 insertions, 9 deletions

diff --git a/Help/guide/tutorial/Step8/MathFunctions/mysqrt.cxx b/Help/guide/tutorial/Step8/MathFunctions/mysqrt.cxx
index 7d80ee9..7eecd26 100644
--- a/Help/guide/tutorial/Step8/MathFunctions/mysqrt.cxx
+++ b/Help/guide/tutorial/Step8/MathFunctions/mysqrt.cxx
@@ -1,10 +1,8 @@
+#include <cmath>
 #include <iostream>
 
 #include "MathFunctions.h"
 
-// include the generated table
-#include "Table.h"
-
 // a hack square root calculation using simple operations
 double mysqrt(double x)
 {
@@ -12,12 +10,13 @@ double mysqrt(double x)
     return 0;
   }
 
-  // use the table to help find an initial value
+  // if we have both log and exp then use them
+#if defined(HAVE_LOG) && defined(HAVE_EXP)
+  double result = std::exp(std::log(x) * 0.5);
+  std::cout << "Computing sqrt of " << x << " to be " << result
+            << " using log and exp" << std::endl;
+#else
   double result = x;
-  if (x >= 1 && x < 10) {
-    std::cout << "Use the table to help find an initial value " << std::endl;
-    result = sqrtTable[static_cast<int>(x)];
-  }
 
   // do ten iterations
   for (int i = 0; i < 10; ++i) {
@@ -28,6 +27,6 @@ double mysqrt(double x)
     result = result + 0.5 * delta / result;
     std::cout << "Computing sqrt of " << x << " to be " << result << std::endl;
   }
-
+#endif
   return result;
 }