cleanng up

Author: mhjensen

doc/Programs/LecturePrograms/programs/IntroProgramming/cpp/derivnofile.cpp

@@ -8,20 +8,17 @@
 
 int main(int argc, char* argv[])
 {
-  double derivative;
-  // Read in output file, abort if there are too few command-line arguments
   if( argc <= 2 ){
     std::cout << "Bad Usage: " << argv[0] <<
-      " read number of integration points" << std::endl;
+      " read step size and value of x" << std::endl;
     exit(1);
   }
   // extracting number of mesh points
-  int i = atoi(argv[1]);
+  double h = atof(argv[1]);
   double x = atof(argv[2]);  // reading x-value
-  double h = 1.0/((double) i); // setting up step size
   double Derivative = (exp(x+h)-2.*exp(x)+exp(x-h))/(h*h);
   double RelativeError = log10(fabs(Derivative-exp(x))/exp(x));
-  std::cout << std::setw(15) << std::setprecision(8) << "relative error=" << RelativeError << std::endl;
+  std::cout << std::setw(15) << std::setprecision(8) << "Log10 of step size=" << log10(h) << " Log10 of relative error=" << RelativeError << std::endl;
   return 0;
 }