tmainD.cpp.html - numeric - C++ library with numerical algorithms
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56 <pre id='vimCodeElement'>
57 <span id="L1" class="LineNr"> 1 </span><span class="PreProc">#include </span><span class="Constant"><iostream></span>
58 <span id="L2" class="LineNr"> 2 </span><span class="PreProc">#include </span><span class="Constant"><vector></span>
59 <span id="L3" class="LineNr"> 3 </span><span class="PreProc">#include </span><span class="Constant"><complex></span>
60 <span id="L4" class="LineNr"> 4 </span><span class="PreProc">#include </span><span class="Constant"><cmath></span>
61 <span id="L5" class="LineNr"> 5 </span><span class="PreProc">#include </span><span class="Constant"><fstream></span>
62 <span id="L6" class="LineNr"> 6 </span><span class="PreProc">#include </span><span class="Constant">"typedefs.h"</span>
63 <span id="L7" class="LineNr"> 7 </span><span class="PreProc">#include </span><span class="Constant">"check.h"</span>
64 <span id="L8" class="LineNr"> 8 </span><span class="PreProc">#include </span><span class="Constant">"ode.h"</span>
65 <span id="L9" class="LineNr"> 9 </span><span class="PreProc">#include </span><span class="Constant">"functions.h"</span>
66 <span id="L10" class="LineNr">10 </span>
67 <span id="L11" class="LineNr">11 </span>
68 <span id="L12" class="LineNr">12 </span><span class="Type">int</span> main()
69 <span id="L13" class="LineNr">13 </span>{
70 <span id="L14" class="LineNr">14 </span> <span class="Comment">// Namespace declarations</span>
71 <span id="L15" class="LineNr">15 </span> <span class="Statement">using</span> std::cout;
72 <span id="L16" class="LineNr">16 </span> <span class="Statement">using</span> std::vector;
73 <span id="L17" class="LineNr">17 </span> <span class="Statement">using</span> std::<span class="Type">complex</span>;
74 <span id="L18" class="LineNr">18 </span>
75 <span id="L19" class="LineNr">19 </span> <span class="Comment">// Calculate machine precision</span>
76 <span id="L20" class="LineNr">20 </span> Floattype eps_machine = <span class="Constant">1.0f</span>;
77 <span id="L21" class="LineNr">21 </span> <span class="Statement">while</span> (<span class="Constant">1.0f</span> + eps_machine != <span class="Constant">1.0f</span>)
78 <span id="L22" class="LineNr">22 </span> eps_machine /= <span class="Constant">2.0f</span>;
79 <span id="L23" class="LineNr">23 </span>
80 <span id="L24" class="LineNr">24 </span> cout << <span class="Constant">"</span><span class="Special">\n\033</span><span class="Constant">[1;33m--- Part D: Precision analysis ---</span><span class="Special">\033</span><span class="Constant">[0m</span><span class="Special">\n</span><span class="Constant">"</span>;
81 <span id="L25" class="LineNr">25 </span> <span class="Type">complex</span><Floattype> a(<span class="Constant">0.0f</span>, <span class="Constant">0.0f</span>); <span class="Comment">// Lower limit</span>
82 <span id="L26" class="LineNr">26 </span> <span class="Type">complex</span><Floattype> b(<span class="Constant">2.0f</span>*<span class="Constant">M_PI</span>, <span class="Constant">2.0f</span>*<span class="Constant">M_PI</span>); <span class="Comment">// Upper limit</span>
83 <span id="L27" class="LineNr">27 </span> cout << <span class="Constant">"Integration path: b-a = "</span> << b-a << <span class="Special">'\n'</span>;
84 <span id="L28" class="LineNr">28 </span> Inttype n_eqs = <span class="Constant">2</span>; <span class="Comment">// Number of equations in ODE system</span>
85 <span id="L29" class="LineNr">29 </span> vector<<span class="Type">complex</span><Floattype> > y_start(n_eqs);
86 <span id="L30" class="LineNr">30 </span> <span class="Type">complex</span><Floattype> y0(<span class="Constant">0.0f</span>, <span class="Constant">0.0f</span>);
87 <span id="L31" class="LineNr">31 </span> <span class="Type">complex</span><Floattype> y1(<span class="Constant">1.0f</span>, <span class="Constant">1.0f</span>);
88 <span id="L32" class="LineNr">32 </span> y_start[<span class="Constant">0</span>] = y0;
89 <span id="L33" class="LineNr">33 </span> y_start[<span class="Constant">1</span>] = y1;
90 <span id="L34" class="LineNr">34 </span> Floattype h_start = <span class="Constant">0.01f</span>;
91 <span id="L35" class="LineNr">35 </span>
92 <span id="L36" class="LineNr">36 </span> vector<Floattype> precs; <span class="Comment">// Vector containing precision values</span>
93 <span id="L37" class="LineNr">37 </span> vector<Inttype> steps; <span class="Comment">// Vector containing number of steps required</span>
94 <span id="L38" class="LineNr">38 </span>
95 <span id="L39" class="LineNr">39 </span> <span class="Statement">for</span> (Floattype prec=eps_machine*<span class="Constant">10.0f</span>; prec<<span class="Constant">0.1f</span>; prec *= <span class="Constant">10.0f</span>) {
96 <span id="L40" class="LineNr">40 </span> ODE ode(func1, <span class="Comment">// ODE system</span>
97 <span id="L41" class="LineNr">41 </span> y_start, <span class="Comment">// Initial values</span>
98 <span id="L42" class="LineNr">42 </span> a, <span class="Comment">// Lower limit</span>
99 <span id="L43" class="LineNr">43 </span> b, <span class="Comment">// Upper limit</span>
100 <span id="L44" class="LineNr">44 </span> h_start, <span class="Comment">// Start value of step size</span>
101 <span id="L45" class="LineNr">45 </span> <span class="Constant">100000</span>, <span class="Comment">// Max. number of steps</span>
102 <span id="L46" class="LineNr">46 </span> prec, <span class="Comment">// Absolute precision</span>
103 <span id="L47" class="LineNr">47 </span> prec); <span class="Comment">// Relative precision</span>
104 <span id="L48" class="LineNr">48 </span> precs.push_back(prec); <span class="Comment">// Save precision</span>
105 <span id="L49" class="LineNr">49 </span> steps.push_back(ode.steps()); <span class="Comment">// Save number of steps taken</span>
106 <span id="L50" class="LineNr">50 </span> }
107 <span id="L51" class="LineNr">51 </span>
108 <span id="L52" class="LineNr">52 </span> <span class="Comment">// Save results to text file</span>
109 <span id="L53" class="LineNr">53 </span> std::ofstream ost; <span class="Comment">// Out stream object</span>
110 <span id="L54" class="LineNr">54 </span> ost.open(<span class="Constant">"funcD.dat"</span>); <span class="Comment">// Open outfile for write</span>
111 <span id="L55" class="LineNr">55 </span> <span class="Statement">if</span> (!ost) {
112 <span id="L56" class="LineNr">56 </span> std::cerr << <span class="Constant">"Error, can't open output file!</span><span class="Special">\n</span><span class="Constant">"</span>;
113 <span id="L57" class="LineNr">57 </span> <span class="Statement">return</span> <span class="Constant">1</span>;
114 <span id="L58" class="LineNr">58 </span> }
115 <span id="L59" class="LineNr">59 </span> <span class="Comment">// Write output values</span>
116 <span id="L60" class="LineNr">60 </span> <span class="Statement">for</span> (Inttype i=<span class="Constant">0</span>; i<precs.size(); ++i)
117 <span id="L61" class="LineNr">61 </span> ost << precs[i] << <span class="Special">'\t'</span> << steps[i] << <span class="Special">'\n'</span>;
118 <span id="L62" class="LineNr">62 </span>
119 <span id="L63" class="LineNr">63 </span> <span class="Comment">// Close file</span>
120 <span id="L64" class="LineNr">64 </span> ost.close();
121 <span id="L65" class="LineNr">65 </span>
122 <span id="L66" class="LineNr">66 </span> <span class="Comment">// Return successfully</span>
123 <span id="L67" class="LineNr">67 </span> <span class="Statement">return</span> <span class="Constant">0</span>;
124 <span id="L68" class="LineNr">68 </span>}
125 </pre>
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