init

Step6/MathFunctions/CMakeLists.txt

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+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}
+          )
+
+# link our compiler flags interface library
+target_link_libraries(MathFunctions tutorial_compiler_flags)
+
+# install libs
+set(installable_libs MathFunctions tutorial_compiler_flags)
+install(TARGETS ${installable_libs} DESTINATION lib)
+# install include headers
+install(FILES MathFunctions.h DESTINATION include)

Step6/MathFunctions/MathFunctions.h

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+double mysqrt(double x);

Step6/MathFunctions/mysqrt.cxx

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+#include <iostream>
+
+#include "MathFunctions.h"
+
+// 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;
+}