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	tmainD.cpp - numeric - C++ library with numerical algorithms
	git clone git://src.adamsgaard.dk/numeric
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	---
	tmainD.cpp (1871B)
	---
	1 #include <iostream>
	2 #include <vector>
	3 #include <complex>
	4 #include <cmath>
	5 #include <fstream>
	6 #include "typedefs.h"
	7 #include "check.h"
	8 #include "ode.h"
	9 #include "functions.h"
	10
	11
	12 int main()
	13 {
	14 // Namespace declarations
	15 using std::cout;
	16 using std::vector;
	17 using std::complex;
	18
	19 // Calculate machine precision
	20 Floattype eps_machine = 1.0f;
	21 while (1.0f + eps_machine != 1.0f)
	22 eps_machine /= 2.0f;
	23
	24 cout << "\n\033[1;33m--- Part D: Precision analysis ---\033[0m\n";
	25 complex<Floattype> a(0.0f, 0.0f); // Lower limit
	26 complex<Floattype> b(2.0fM_PI, 2.0fM_PI); // Upper limit
	27 cout << "Integration path: b-a = " << b-a << '\n';
	28 Inttype n_eqs = 2; // Number of equations in ODE system
	29 vector<complex<Floattype> > y_start(n_eqs);
	30 complex<Floattype> y0(0.0f, 0.0f);
	31 complex<Floattype> y1(1.0f, 1.0f);
	32 y_start[0] = y0;
	33 y_start[1] = y1;
	34 Floattype h_start = 0.01f;
	35
	36 vector<Floattype> precs; // Vector containing precision values
	37 vector<Inttype> steps; // Vector containing number of steps required
	38
	39 for (Floattype prec=eps_machine10.0f; prec<0.1f; prec = 10.0f) {
	40 ODE ode(func1, // ODE system
	41 y_start, // Initial values
	42 a, // Lower limit
	43 b, // Upper limit
	44 h_start, // Start value of step size
	45 100000, // Max. number of steps
	46 prec, // Absolute precision
	47 prec); // Relative precision
	48 precs.push_back(prec); // Save precision
	49 steps.push_back(ode.steps()); // Save number of steps taken
	50 }
	51
	52 // Save results to text file
	53 std::ofstream ost; // Out stream object
	54 ost.open("funcD.dat"); // Open outfile for write
	55 if (!ost) {
	56 std::cerr << "Error, can't open output file!\n";
	57 return 1;
	58 }
	59 // Write output values
	60 for (Inttype i=0; i<precs.size(); ++i)
	61 ost << precs[i] << '\t' << steps[i] << '\n';
	62
	63 // Close file
	64 ost.close();
	65
	66 // Return successfully
	67 return 0;
	68 }