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<h1>Gammaq.cxx</h1><a href="Gammaq_8cxx.html">Go to the documentation of this file.</a><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001
<a name="l00010"></a>00010 <span class="preprocessor">#include "<a class="code" href="Gammaq_8h.html" title="Declaration of GammaQ functions.">Gammaq.h</a>"</span>
<a name="l00011"></a>00011
<a name="l00012"></a>00012 <span class="preprocessor">#include <iostream></span>
<a name="l00013"></a>00013
<a name="l00014"></a>00014 <span class="preprocessor">#include <cassert></span>
<a name="l00015"></a>00015 <span class="preprocessor">#include <cmath></span>
<a name="l00016"></a>00016
<a name="l00017"></a>00017 <span class="keyword">using</span> std::cerr;
<a name="l00018"></a>00018 <span class="keyword">using</span> std::endl;
<a name="l00019"></a>00019 <span class="keyword">using</span> std::abs;
<a name="l00020"></a>00020
<a name="l00021"></a>00021 <span class="keyword">namespace </span>hippodraw {
<a name="l00022"></a><a class="code" href="namespacehippodraw_1_1Numeric.html">00022</a> <span class="keyword">namespace </span>Numeric {
<a name="l00023"></a>00023
<a name="l00024"></a>00024 <span class="keywordtype">double</span> <a class="code" href="namespacehippodraw_1_1Numeric.html#ae01374ddda83bc2216ba9df9c76d9995" title="Calculates natural log of a gamma function.">gammln</a>( <span class="keywordtype">double</span> xx )
<a name="l00025"></a>00025 {
<a name="l00026"></a>00026 <span class="keywordtype">double</span> x, y, tmp, ser;
<a name="l00027"></a>00027 <span class="keyword">static</span> <span class="keywordtype">double</span> cof[6]={76.18009172947146,-86.50532032941677,
<a name="l00028"></a>00028 24.01409824083091,-1.231739572450155,
<a name="l00029"></a>00029 0.1208650973866179e-2,-0.5395239384953e-5};
<a name="l00030"></a>00030
<a name="l00031"></a>00031 y = x = xx;
<a name="l00032"></a>00032 tmp = x + 5.5;
<a name="l00033"></a>00033 tmp -= ( x + 0.5 ) * log( tmp );
<a name="l00034"></a>00034 ser = 1.000000000190015;
<a name="l00035"></a>00035
<a name="l00036"></a>00036 <span class="keywordflow">for</span> ( <span class="keywordtype">int</span> j = 0; j <= 5; j++)
<a name="l00037"></a>00037 ser += cof[j] / (++y);
<a name="l00038"></a>00038
<a name="l00039"></a>00039 <span class="keywordflow">return</span> -tmp + log( 2.5066282746310005 * ser / x);
<a name="l00040"></a>00040 }
<a name="l00041"></a>00041
<a name="l00042"></a>00042
<a name="l00043"></a>00043 <span class="keywordtype">void</span> <a class="code" href="namespacehippodraw_1_1Numeric.html#a5277079b0c65d166db9553deb8a92de2" title="Calculates Q, the probability that the chi2 should exceed a particilar chi2 (input)...">gser</a>(<span class="keywordtype">double</span> *gamser, <span class="keywordtype">double</span> a, <span class="keywordtype">double</span> x, <span class="keywordtype">double</span> *gln)
<a name="l00044"></a>00044 {
<a name="l00045"></a>00045 <span class="keywordtype">int</span> n;
<a name="l00046"></a>00046 <span class="keywordtype">double</span> sum, del, ap;
<a name="l00047"></a>00047
<a name="l00048"></a>00048 *gln = <a class="code" href="namespacehippodraw_1_1Numeric.html#ae01374ddda83bc2216ba9df9c76d9995" title="Calculates natural log of a gamma function.">gammln</a>( a );
<a name="l00049"></a>00049
<a name="l00050"></a>00050 <span class="keywordflow">if</span> ( x <= 0.0 )
<a name="l00051"></a>00051 {
<a name="l00052"></a>00052 <span class="keywordflow">if</span> (x < 0.0) cerr << <span class="stringliteral">"Error: x less than 0 in routine gser"</span> << endl;
<a name="l00053"></a>00053 *gamser=0.0;
<a name="l00054"></a>00054 <span class="keywordflow">return</span>;
<a name="l00055"></a>00055 }
<a name="l00056"></a>00056 <span class="keywordflow">else</span>
<a name="l00057"></a>00057 {
<a name="l00058"></a>00058 ap = a;
<a name="l00059"></a>00059 del = sum =1.0 / a;
<a name="l00060"></a>00060 <span class="keywordflow">for</span> (n = 1; n <= <a class="code" href="Gammaq_8h.html#a3641b6d4c21b7a852dbb32c2b693302e">ITMAX</a>; n++)
<a name="l00061"></a>00061 {
<a name="l00062"></a>00062 ++ap;
<a name="l00063"></a>00063 del *= x/ap;
<a name="l00064"></a>00064 sum += del;
<a name="l00065"></a>00065
<a name="l00066"></a>00066 <span class="keywordflow">if</span> (abs(del) < abs(sum)*<a class="code" href="Gammaq_8h.html#a6ebf6899d6c1c8b7b9d09be872c05aae">EPS</a>)
<a name="l00067"></a>00067 {
<a name="l00068"></a>00068 *gamser = sum * exp( -x + a * log( x ) -( *gln ) );
<a name="l00069"></a>00069 <span class="keywordflow">return</span>;
<a name="l00070"></a>00070 }
<a name="l00071"></a>00071 }
<a name="l00072"></a>00072
<a name="l00073"></a>00073 cerr << <span class="stringliteral">"ERROR: a too large, ITMAX too small in routine gser"</span> << endl;
<a name="l00074"></a>00074 <span class="keywordflow">return</span>;
<a name="l00075"></a>00075 }
<a name="l00076"></a>00076 }
<a name="l00077"></a>00077
<a name="l00078"></a>00078 <span class="keywordtype">void</span> <a class="code" href="namespacehippodraw_1_1Numeric.html#a5b446e3e8ec13c8e2383ac156f0cf77f" title="Calculates Q, the probability that the chi2 should exceed a particilar chi2 (input)...">gcf</a>( <span class="keywordtype">double</span> *gammcf, <span class="keywordtype">double</span> a, <span class="keywordtype">double</span> x, <span class="keywordtype">double</span> *gln )
<a name="l00079"></a>00079 {
<a name="l00080"></a>00080 <span class="keywordtype">int</span> i;
<a name="l00081"></a>00081 <span class="keywordtype">double</span> an,b,c,d,del,h;
<a name="l00082"></a>00082
<a name="l00083"></a>00083 *gln = <a class="code" href="namespacehippodraw_1_1Numeric.html#ae01374ddda83bc2216ba9df9c76d9995" title="Calculates natural log of a gamma function.">gammln</a>( a );
<a name="l00084"></a>00084 b = x + 1.0 - a;
<a name="l00085"></a>00085 c = 1.0 / <a class="code" href="Gammaq_8h.html#a54a4e9f9387854c492c138ece3fc2279">FPMIN</a>;
<a name="l00086"></a>00086 d = 1.0 / b;
<a name="l00087"></a>00087 h = d;
<a name="l00088"></a>00088
<a name="l00089"></a>00089 <span class="keywordflow">for</span>( i = 1; i <= <a class="code" href="Gammaq_8h.html#a3641b6d4c21b7a852dbb32c2b693302e">ITMAX</a>; i++ )
<a name="l00090"></a>00090 {
<a name="l00091"></a>00091 an = -i*(i-a);
<a name="l00092"></a>00092 b += 2.0;
<a name="l00093"></a>00093 d=an*d+b;
<a name="l00094"></a>00094
<a name="l00095"></a>00095 <span class="keywordflow">if</span> ( abs( d ) < <a class="code" href="Gammaq_8h.html#a54a4e9f9387854c492c138ece3fc2279">FPMIN</a> )
<a name="l00096"></a>00096 d = <a class="code" href="Gammaq_8h.html#a54a4e9f9387854c492c138ece3fc2279">FPMIN</a>;
<a name="l00097"></a>00097
<a name="l00098"></a>00098 c = b + an / c;
<a name="l00099"></a>00099
<a name="l00100"></a>00100 <span class="keywordflow">if</span> ( abs( c ) < <a class="code" href="Gammaq_8h.html#a54a4e9f9387854c492c138ece3fc2279">FPMIN</a> )
<a name="l00101"></a>00101 c = <a class="code" href="Gammaq_8h.html#a54a4e9f9387854c492c138ece3fc2279">FPMIN</a>;
<a name="l00102"></a>00102
<a name="l00103"></a>00103 d = 1.0 / d;
<a name="l00104"></a>00104 del = d * c;
<a name="l00105"></a>00105 h *= del;
<a name="l00106"></a>00106
<a name="l00107"></a>00107 <span class="keywordflow">if</span> ( abs( del - 1.0 ) < <a class="code" href="Gammaq_8h.html#a6ebf6899d6c1c8b7b9d09be872c05aae">EPS</a>)
<a name="l00108"></a>00108 <span class="keywordflow">break</span>;
<a name="l00109"></a>00109 }
<a name="l00110"></a>00110
<a name="l00111"></a>00111 <span class="keywordflow">if</span> (i > <a class="code" href="Gammaq_8h.html#a3641b6d4c21b7a852dbb32c2b693302e">ITMAX</a>) cerr << <span class="stringliteral">"a too large, ITMAX too small in gcf"</span> << endl;
<a name="l00112"></a>00112
<a name="l00113"></a>00113 *gammcf = exp( -x + a * log( x ) -( *gln ) ) * h;
<a name="l00114"></a>00114 }
<a name="l00115"></a>00115
<a name="l00116"></a>00116 <span class="keywordtype">double</span> <a class="code" href="namespacehippodraw_1_1Numeric.html#a3875415d74d3aaf6f58d9e58fc061efd" title="Calculates Q, the probability that the chi2 should exceed a particilar chi2 (input)...">gammq</a>(<span class="keywordtype">double</span> a, <span class="keywordtype">double</span> x)
<a name="l00117"></a>00117 {
<a name="l00118"></a>00118 <span class="keywordtype">void</span> <a class="code" href="namespacehippodraw_1_1Numeric.html#a5b446e3e8ec13c8e2383ac156f0cf77f" title="Calculates Q, the probability that the chi2 should exceed a particilar chi2 (input)...">gcf</a>(<span class="keywordtype">double</span> *gammcf, <span class="keywordtype">double</span> a, <span class="keywordtype">double</span> x, <span class="keywordtype">double</span> *gln);
<a name="l00119"></a>00119
<a name="l00120"></a>00120 <span class="keywordtype">double</span> gamser,gammcf,gln;
<a name="l00121"></a>00121
<a name="l00122"></a>00122 <span class="keywordflow">if</span> (x < 0.0 || a <= 0.0)
<a name="l00123"></a>00123 {
<a name="l00124"></a>00124 cerr << <span class="stringliteral">"a = "</span> << a << <span class="stringliteral">" x = "</span> << x << endl;
<a name="l00125"></a>00125 cerr << <span class="stringliteral">"Invalid arguments in routine GAMMQ"</span> << endl;
<a name="l00126"></a>00126 assert(0);
<a name="l00127"></a>00127 }
<a name="l00128"></a>00128
<a name="l00129"></a>00129 <span class="keywordflow">if</span> (x < (a+1.0))
<a name="l00130"></a>00130 {
<a name="l00131"></a>00131 <a class="code" href="namespacehippodraw_1_1Numeric.html#a5277079b0c65d166db9553deb8a92de2" title="Calculates Q, the probability that the chi2 should exceed a particilar chi2 (input)...">gser</a>(&gamser,a,x,&gln);
<a name="l00132"></a>00132 <span class="keywordflow">return</span> 1.0-gamser;
<a name="l00133"></a>00133 }
<a name="l00134"></a>00134 <span class="keywordflow">else</span>
<a name="l00135"></a>00135 {
<a name="l00136"></a>00136 <a class="code" href="namespacehippodraw_1_1Numeric.html#a5b446e3e8ec13c8e2383ac156f0cf77f" title="Calculates Q, the probability that the chi2 should exceed a particilar chi2 (input)...">gcf</a>(&gammcf,a,x,&gln);
<a name="l00137"></a>00137 <span class="keywordflow">return</span> gammcf;
<a name="l00138"></a>00138 }
<a name="l00139"></a>00139 }
<a name="l00140"></a>00140
<a name="l00141"></a>00141 } <span class="comment">// end namespace Numeric</span>
<a name="l00142"></a>00142 } <span class="comment">// end namespace hippodraw</span>
<a name="l00143"></a>00143
<a name="l00150"></a>00150 <span class="comment">/*</span>
<a name="l00151"></a>00151 <span class="comment">int main(void)</span>
<a name="l00152"></a>00152 <span class="comment">{</span>
<a name="l00153"></a>00153 <span class="comment"> char txt[MAXSTR];</span>
<a name="l00154"></a>00154 <span class="comment"> int i,nval;</span>
<a name="l00155"></a>00155 <span class="comment"> float a,val,x;</span>
<a name="l00156"></a>00156 <span class="comment"> FILE *fp;</span>
<a name="l00157"></a>00157 <span class="comment"> </span>
<a name="l00158"></a>00158 <span class="comment"> if ((fp = fopen("fncval.dat","r")) == NULL)</span>
<a name="l00159"></a>00159 <span class="comment"> printf("Data file fncval.dat not found\n");</span>
<a name="l00160"></a>00160 <span class="comment"></span>
<a name="l00161"></a>00161 <span class="comment"> std::fgets(txt,MAXSTR,fp);</span>
<a name="l00162"></a>00162 <span class="comment"> </span>
<a name="l00163"></a>00163 <span class="comment"> while ( std::strncmp(txt,"Incomplete Gamma Function",25))</span>
<a name="l00164"></a>00164 <span class="comment"> {</span>
<a name="l00165"></a>00165 <span class="comment"> std::fgets(txt,MAXSTR,fp);</span>
<a name="l00166"></a>00166 <span class="comment"> if ( std::feof(fp))</span>
<a name="l00167"></a>00167 <span class="comment"> std::printf("Data not found in fncval.dat\n");</span>
<a name="l00168"></a>00168 <span class="comment"> }</span>
<a name="l00169"></a>00169 <span class="comment"> </span>
<a name="l00170"></a>00170 <span class="comment"> std::fscanf(fp,"%d %*s",&nval);</span>
<a name="l00171"></a>00171 <span class="comment"> std::printf("\n%s\n",txt);</span>
<a name="l00172"></a>00172 <span class="comment"> std::printf("%4s %11s %14s %14s \n","a","x","actual","gammq(a,x)");</span>
<a name="l00173"></a>00173 <span class="comment"></span>
<a name="l00174"></a>00174 <span class="comment"> for (i=1;i<=nval;i++)</span>
<a name="l00175"></a>00175 <span class="comment"> {</span>
<a name="l00176"></a>00176 <span class="comment"> std::fscanf(fp,"%f %f %f",&a,&x,&val);</span>
<a name="l00177"></a>00177 <span class="comment"> std::printf("%6.2f %12.6f %12.6f %12.6f\n", a, x, (1.0-val), gammq(a,x));</span>
<a name="l00178"></a>00178 <span class="comment"> }</span>
<a name="l00179"></a>00179 <span class="comment"> </span>
<a name="l00180"></a>00180 <span class="comment"> std::fclose(fp);</span>
<a name="l00181"></a>00181 <span class="comment"> return 0;</span>
<a name="l00182"></a>00182 <span class="comment">}</span>
<a name="l00183"></a>00183 <span class="comment"></span>
<a name="l00184"></a>00184 <span class="comment">*/</span>
<a name="l00185"></a>00185
<a name="l00186"></a>00186 <span class="preprocessor">#undef ITMAX</span>
<a name="l00187"></a>00187 <span class="preprocessor"></span><span class="preprocessor">#undef EPS</span>
<a name="l00188"></a>00188 <span class="preprocessor"></span><span class="preprocessor">#undef FPMIN</span>
<a name="l00189"></a>00189 <span class="preprocessor"></span><span class="preprocessor">#undef MAXSTR</span>
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