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cdf_69.c
Go to the documentation of this file.00001 #include "cdflib.h"
00002 double rlog(double *x)
00003
00004
00005
00006
00007
00008 {
00009 static double a = .566749439387324e-01;
00010 static double b = .456512608815524e-01;
00011 static double p0 = .333333333333333e+00;
00012 static double p1 = -.224696413112536e+00;
00013 static double p2 = .620886815375787e-02;
00014 static double q1 = -.127408923933623e+01;
00015 static double q2 = .354508718369557e+00;
00016 static double rlog,r,t,u,w,w1;
00017
00018
00019
00020
00021 if(*x < 0.61e0 || *x > 1.57e0) goto S40;
00022 if(*x < 0.82e0) goto S10;
00023 if(*x > 1.18e0) goto S20;
00024
00025
00026
00027 u = *x-0.5e0-0.5e0;
00028 w1 = 0.0e0;
00029 goto S30;
00030 S10:
00031 u = *x-0.7e0;
00032 u /= 0.7e0;
00033 w1 = a-u*0.3e0;
00034 goto S30;
00035 S20:
00036 u = 0.75e0**x-1.e0;
00037 w1 = b+u/3.0e0;
00038 S30:
00039
00040
00041
00042 r = u/(u+2.0e0);
00043 t = r*r;
00044 w = ((p2*t+p1)*t+p0)/((q2*t+q1)*t+1.0e0);
00045 rlog = 2.0e0*t*(1.0e0/(1.0e0-r)-r*w)+w1;
00046 return rlog;
00047 S40:
00048 r = *x-0.5e0-0.5e0;
00049 rlog = r-log(*x);
00050 return rlog;
00051 }
