text: // xllproject.cpp
  #include <cmath>
  #include "hw13.h"
  
  using namespace xll;
  
  AddIn xai_project(
      Document(L"hw13")
      .Documentation(
          L"This will generate a Sandcastle Helpfile Builder project file. "
          L"Start Excel with the add-in loaded and run (Alt-F8) the macro MAKE.SHFB. "
      )
  );
  
  AddIn xai_xllproject(
      Document(CATEGORY)
      .Category(CATEGORY)
      .Documentation(
          L"Documentation for the " CATEGORY L" category. "
          L"<para>"
          L"The function XLL.PWLINEAR.VALUE(x, y, f, p, c) computes the value "
          L"of a piecwise linear payoff determinded by x and y "
          L"using put prices (x < f) and call prices (x > f). "
          L"</para>"
          L"<para>"
          L"We assume f is par forward value of the underlying. "
          L"</para>"
      )
  );
  
  //!!! Implement XLL.PWLINEAR.VALUE as described above.