mirror of https://github.com/flysand7/ciabatta.git
77 lines
2.8 KiB
C
77 lines
2.8 KiB
C
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#include <stdio.h>
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#include <math.h>
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#include <float.h>
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#include <fenv.h>
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const char *show_classification(double x) {
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switch(fpclassify(x)) {
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case FP_INFINITE: return "Inf";
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case FP_NAN: return "NaN";
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case FP_NORMAL: return "normal";
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case FP_SUBNORMAL: return "subnormal";
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case FP_ZERO: return "zero";
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default: return "unknown";
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}
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}
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int main() {
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printf("\n=== fpclassify === \n");
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double zero = 0.0; // fucken msvc
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printf("1.0/0.0 is %s\n", show_classification(1.0/zero));
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printf("0.0/0.0 is %s\n", show_classification(0.0/zero));
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printf("DBL_MIN/2 is %s\n", show_classification(DBL_MIN/2));
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printf("-0.0 is %s\n", show_classification(-0.0));
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printf("1.0 is %s\n", show_classification(1.0));
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printf("\n\n=== signbit === \n");
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printf("signbit(+0.0) = %d\n", signbit(+0.0));
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printf("signbit(-0.0) = %d\n", signbit(-0.0));
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printf("\n\n=== copysign === \n");
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printf("copysign(1.0,+2.0) = %f\n", copysign(1.0,+2.0));
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printf("copysign(1.0,-2.0) = %f\n", copysign(1.0,-2.0));
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printf("copysign(INFINITY,-2.0) = %f\n", copysign(INFINITY,-2.0));
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printf("copysign(NAN,-2.0) = %f\n", copysign(NAN,-2.0));
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printf("\n\n=== rint === \n");
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fesetround(FE_TONEAREST);
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printf("rounding to nearest (halfway cases to even):\n"
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"rint(+2.3) = %f ", rint(2.3));
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printf("rint(+2.5) = %f ", rint(2.5));
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printf("rint(+3.5) = %f\n", rint(3.5));
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printf("rint(-2.3) = %f ", rint(-2.3));
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printf("rint(-2.5) = %f ", rint(-2.5));
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printf("rint(-3.5) = %f\n", rint(-3.5));
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fesetround(FE_DOWNWARD);
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printf("rounding down: \nrint(+2.3) = %f ", rint(2.3));
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printf("rint(+2.5) = %f ", rint(2.5));
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printf("rint(+3.5) = %f\n", rint(3.5));
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printf("rint(-2.3) = %f ", rint(-2.3));
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printf("rint(-2.5) = %f ", rint(-2.5));
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printf("rint(-3.5) = %f\n", rint(-3.5));
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feclearexcept(FE_ALL_EXCEPT);
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printf("rint(1.1) = %f\n", rint(1.1));
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if(fetestexcept(FE_INEXACT)) printf(" FE_INEXACT was raised\n");
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float from1 = 0, to1 = nextafterf(from1, 1);
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printf("The next representable float after %f is %f\n", from1, to1);
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float from2 = 1, to2 = nextafterf(from2, 2);
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printf("The next representable float after %f is %f\n", from2, to2);
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{
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#pragma STDC FENV_ACCESS ON
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feclearexcept(FE_ALL_EXCEPT);
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double from4 = DBL_MAX, to4 = nextafter(from4, INFINITY);
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printf("The next representable double after %f is %f\n",
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from4, to4);
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if(fetestexcept(FE_OVERFLOW)) printf(" raised FE_OVERFLOW\n");
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if(fetestexcept(FE_INEXACT)) printf(" raised FE_INEXACT\n");
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}
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float from5 = 0.0, to5 = nextafter(from5, -0.0);
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printf("nextafter(+0.0, -0.0) gives %f (%f)\n", to5, to5);
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return 0;
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}
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