4 files changed, 73 insertions, 0 deletions
diff --git a/Help/guide/tutorial/Step6/MathFunctions/CMakeLists.txt b/Help/guide/tutorial/Step6/MathFunctions/CMakeLists.txt
new file mode 100644
index 0000000..2946075
--- /dev/null
+++ b/Help/guide/tutorial/Step6/MathFunctions/CMakeLists.txt
@@ -0,0 +1,14 @@
+add_library(MathFunctions mysqrt.cxx)
+
+# state that anybody linking to us needs to include the current source dir
+# to find MathFunctions.h, while we don't.
+# state that we depend on Tutorial_BINARY_DIR but consumers don't, as the
+# TutorialConfig.h include is an implementation detail
+
+target_include_directories(MathFunctions
+          INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}
+          PRIVATE ${Tutorial_BINARY_DIR}
+          )
+
+install(TARGETS MathFunctions DESTINATION lib)
+install(FILES MathFunctions.h DESTINATION include)
diff --git a/Help/guide/tutorial/Step6/MathFunctions/MakeTable.cxx b/Help/guide/tutorial/Step6/MathFunctions/MakeTable.cxx
new file mode 100644
index 0000000..ee58556
--- /dev/null
+++ b/Help/guide/tutorial/Step6/MathFunctions/MakeTable.cxx
@@ -0,0 +1,25 @@
+// A simple program that builds a sqrt table
+#include <cmath>
+#include <fstream>
+#include <iostream>
+
+int main(int argc, char* argv[])
+{
+  // make sure we have enough arguments
+  if (argc < 2) {
+    return 1;
+  }
+
+  std::ofstream fout(argv[1], std::ios_base::out);
+  const bool fileOpen = fout.is_open();
+  if (fileOpen) {
+    fout << "double sqrtTable[] = {" << std::endl;
+    for (int i = 0; i < 10; ++i) {
+      fout << sqrt(static_cast<double>(i)) << "," << std::endl;
+    }
+    // close the table with a zero
+    fout << "0};" << std::endl;
+    fout.close();
+  }
+  return fileOpen ? 0 : 1; // return 0 if wrote the file
+}
diff --git a/Help/guide/tutorial/Step6/MathFunctions/MathFunctions.h b/Help/guide/tutorial/Step6/MathFunctions/MathFunctions.h
new file mode 100644
index 0000000..cd36bcc
--- /dev/null
+++ b/Help/guide/tutorial/Step6/MathFunctions/MathFunctions.h
@@ -0,0 +1 @@
+double mysqrt(double x);
diff --git a/Help/guide/tutorial/Step6/MathFunctions/mysqrt.cxx b/Help/guide/tutorial/Step6/MathFunctions/mysqrt.cxx
new file mode 100644
index 0000000..b9ad20a
--- /dev/null
+++ b/Help/guide/tutorial/Step6/MathFunctions/mysqrt.cxx
@@ -0,0 +1,33 @@
+#include "MathFunctions.h"
+#include "TutorialConfig.h"
+#include <iostream>
+
+#include <cmath>
+
+// a hack square root calculation using simple operations
+double mysqrt(double x)
+{
+  if (x <= 0) {
+    return 0;
+  }
+
+  // if we have both log and exp then use them
+#if defined(HAVE_LOG) && defined(HAVE_EXP)
+  double result = exp(log(x) * 0.5);
+  std::cout << "Computing sqrt of " << x << " to be " << result << " using log"
+            << std::endl;
+#else
+  double result = x;
+
+  // do ten iterations
+  for (int i = 0; i < 10; ++i) {
+    if (result <= 0) {
+      result = 0.1;
+    }
+    double delta = x - (result * result);
+    result = result + 0.5 * delta / result;
+    std::cout << "Computing sqrt of " << x << " to be " << result << std::endl;
+  }
+#endif
+  return result;
+}