e5c844eff2
- Smaller C: fix a bug in __func__ introduced with
float-related changes
- make *printf() print floats greater than 1e25
- make *printf() print the plus sign when the format
includes "+", e.g. printf("%+f\n", 1.0);
- clean up and complete prototypes in <math.h>
- remove non-standard HUGE and LOGHUGE from <math.h>
- add HUGE_VAL to <math.h>
- express some hard-coded limits in terms of constants
from <float.h>
- uncomment prototypes of several floating point
conversion functions in <stdlib.h> for Smaller C
74 lines
1.3 KiB
C
74 lines
1.3 KiB
C
/*
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* floating point tangent
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*
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* A series is used after range reduction.
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* Coefficients are #4285 from Hart & Cheney. (19.74D)
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*/
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#include <errno.h>
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#include <math.h>
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int errno;
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static double invpi = 1.27323954473516268;
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static double p0 = -0.1306820264754825668269611177e+5;
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static double p1 = 0.1055970901714953193602353981e+4;
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static double p2 = -0.1550685653483266376941705728e+2;
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static double p3 = 0.3422554387241003435328470489e-1;
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static double p4 = 0.3386638642677172096076369e-4;
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static double q0 = -0.1663895238947119001851464661e+5;
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static double q1 = 0.4765751362916483698926655581e+4;
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static double q2 = -0.1555033164031709966900124574e+3;
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double
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tan(arg)
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double arg;
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{
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double modf();
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double sign, temp, e, x, xsq;
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int flag, i;
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flag = 0;
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sign = 1.;
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if(arg < 0.){
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arg = -arg;
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sign = -1.;
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}
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arg = arg*invpi; /*overflow?*/
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x = modf(arg,&e);
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i = e;
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switch(i%4) {
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case 1:
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x = 1. - x;
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flag = 1;
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break;
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case 2:
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sign = - sign;
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flag = 1;
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break;
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case 3:
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x = 1. - x;
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sign = - sign;
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break;
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case 0:
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break;
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}
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xsq = x*x;
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temp = ((((p4*xsq+p3)*xsq+p2)*xsq+p1)*xsq+p0)*x;
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temp = temp/(((1.0*xsq+q2)*xsq+q1)*xsq+q0);
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if(flag == 1) {
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if(temp == 0.) {
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errno = ERANGE;
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if (sign>0)
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return(HUGE_VAL);
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return(-HUGE_VAL);
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}
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temp = 1./temp;
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}
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return(sign*temp);
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}
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