Merge topic 'help-guide-tutorial'

8ab8563533 Help: Add tutorial guide table of contents
0a6c9c417a Help: Update tutorial to include text from CMake book
eef3e020c2 Help: Populate tutorial guide text
862cfc0e6c Help/guide/tutorial: Adopt tutorial code
d2fde94809 Help: Add infrastructure for guide-level documentation
f067af8e38 Tests/Tutorial: Remove trailing blank lines
d5a81ef747 Tests/Tutorial: Remove unused file

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !3439

3 files changed, 31 insertions, 0 deletions

diff --git a/Help/guide/tutorial/Step4/MathFunctions/CMakeLists.txt b/Help/guide/tutorial/Step4/MathFunctions/CMakeLists.txt
new file mode 100644
index 0000000..0515852
--- /dev/null
+++ b/Help/guide/tutorial/Step4/MathFunctions/CMakeLists.txt
@@ -0,0 +1,7 @@
+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.
+target_include_directories(MathFunctions
+          INTERFACE ${CMAKE_CURRENT_SOURCE_DIR}
+          )
diff --git a/Help/guide/tutorial/Step4/MathFunctions/MathFunctions.h b/Help/guide/tutorial/Step4/MathFunctions/MathFunctions.h
new file mode 100644
index 0000000..cd36bcc
--- /dev/null
+++ b/Help/guide/tutorial/Step4/MathFunctions/MathFunctions.h
@@ -0,0 +1 @@
+double mysqrt(double x);
diff --git a/Help/guide/tutorial/Step4/MathFunctions/mysqrt.cxx b/Help/guide/tutorial/Step4/MathFunctions/mysqrt.cxx
new file mode 100644
index 0000000..7d9379e
--- /dev/null
+++ b/Help/guide/tutorial/Step4/MathFunctions/mysqrt.cxx
@@ -0,0 +1,23 @@
+#include "MathFunctions.h"
+#include <iostream>
+
+// a hack square root calculation using simple operations
+double mysqrt(double x)
+{
+  if (x <= 0) {
+    return 0;
+  }
+
+  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;
+  }
+  return result;
+}