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cdf_45.c File Reference
#include "cdflib.h"Go to the source code of this file.
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| double | dln1px (double *a) |
Function Documentation
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Definition at line 2 of file cdf_45.c. Referenced by dlanor(), dln1mx(), and dln1px().
00029 :
00030 DiDinato, A. R. and Morris, A. H. Algorithm 708: Significant
00031 Digit Computation of the Incomplete Beta Function Ratios. ACM
00032 Trans. Math. Softw. 18 (1993), 360-373.
00033
00034 **********************************************************************
00035 -----------------------------------------------------------------------
00036 EVALUATION OF THE FUNCTION LN(1 + A)
00037 -----------------------------------------------------------------------
00038 */
00039 {
00040 static double p1 = -.129418923021993e+01;
00041 static double p2 = .405303492862024e+00;
00042 static double p3 = -.178874546012214e-01;
00043 static double q1 = -.162752256355323e+01;
00044 static double q2 = .747811014037616e+00;
00045 static double q3 = -.845104217945565e-01;
00046 static double dln1px,t,t2,w,x;
00047 /*
00048 ..
00049 .. Executable Statements ..
00050 */
00051 if(fabs(*a) > 0.375e0) goto S10;
00052 t = *a/(*a+2.0e0);
00053 t2 = t*t;
00054 w = (((p3*t2+p2)*t2+p1)*t2+1.0e0)/(((q3*t2+q2)*t2+q1)*t2+1.0e0);
00055 dln1px = 2.0e0*t*w;
00056 return dln1px;
00057 S10:
00058 x = 1.e0+*a;
00059 dln1px = log(x);
00060 return dln1px;
} /* END */
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