Category : C Source Code
Archive   : CSRC2.ZIP
Filename : EXP.C

 
Output of file : EXP.C contained in archive : CSRC2.ZIP
/*
exp returns exponential of floating point argument

the coefficients are #1069 from Hart and Cheney. (22.35D)
*/

static double p0 = 0.2080384346694663001443843411e7;
static double p1 = 0.3028697169744036299076048876e5;
static double p2 = 0.6061485330061080804165584556e2;
static double q0 = 0.6002720360238832528230907598e7;
static double q1 = 0.3277251518082914423057964422e6;
static double q2 = 0.1749287689093076403844945335e4;
static double log2e = 1.4426950408889634073599247;
static double sqrt2 = 1.4142135623730950488016887;

double exp(arg)

double arg;
{
double fract;
double temp1,temp2,xsq;
int ent;
extern double floor();
extern double ldexp();
extern double itof();

if (arg == 0.0) return(1.0);
if (arg < -10000.0) return(0.0);
if (arg > 10000.0) return(.99999999e35);

arg = arg*log2e;
ent = ftoi(floor(arg));
fract = (arg-itof(ent))-0.5;
xsq = fract*fract;
temp1 = ((p2*xsq+p1)*xsq+p0)*fract;
temp2 = ((xsq+q2)*xsq+q1)*xsq+q0;
return(ldexp(sqrt2*(temp2+temp1)/(temp2-temp1),ent));
}


  3 Responses to “Category : C Source Code
Archive   : CSRC2.ZIP
Filename : EXP.C

  1. Very nice! Thank you for this wonderful archive. I wonder why I found it only now. Long live the BBS file archives!

  2. This is so awesome! 😀 I’d be cool if you could download an entire archive of this at once, though.

  3. But one thing that puzzles me is the “mtswslnkmcjklsdlsbdmMICROSOFT” string. There is an article about it here. It is definitely worth a read: http://www.os2museum.com/wp/mtswslnk/