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sinpi, sinpif, sinpil, sinpid32, sinpid64, sinpid128

From cppreference.com
< c‎ | numeric‎ | math
 
 
 
Common mathematical functions
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sinpi
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Defined in header <math.h>
float       sinpif( float arg );
(1) (since C23)
double      sinpi( double arg );
(2) (since C23)
long double sinpil( long double arg );
(3) (since C23)
_Decimal32  sinpid32( _Decimal32 arg );
(4) (since C23)
_Decimal64  sinpid64( _Decimal64 arg );
(5) (since C23)
_Decimal128 sinpid128( _Decimal128 arg );
(6) (since C23)
Defined in header <tgmath.h>
#define sinpi( arg )
(7) (since C23)
1-6) Computes the sine of π·arg measured in radians, thus regarding arg as a measurement in half-revolutions.
7) Type-generic macro: calls the correct function based on the type of arg. If the argument has integer type, (2) is called.

The functions (4-6) are declared if and only if the implementation predefines __STDC_IEC_60559_DFP__ (i.e. the implementation supports decimal floating-point numbers).

(since C23)

Contents

[edit] Parameters

arg - floating-point value whose product with π represents an angle in radians

[edit] Return value

If no errors occur, the sine of π·arg (sin(π×arg)) in the range [-1, +1], is returned.

[edit] Error handling

Errors are reported as specified in math_errhandling.

If the implementation supports IEEE floating-point arithmetic (IEC 60559):

  • if the argument is ±0, it is returned unmodified;
  • if the argument is ±∞, NaN is returned and FE_INVALID is raised;
  • if the argument is NaN, NaN is returned.

[edit] Example

#include <errno.h>
#include <fenv.h>
#include <math.h>
#include <stdio.h>
 
#ifndef __GNUC__
#pragma STDC FENV_ACCESS ON
#endif
 
#if __STDC_VERSION__ < 202311L
// A naive implementation of a subset of sinpi family
double sinpi(double arg)
{
    return sin(arg * (double)3.1415926535897932384626433);
}
#endif
 
int main(void)
{
    const double pi = acos(-1);
 
    // typical usage
    printf("sinpi(1) = %f, sin(pi) = %f\n", sinpi(1), sin(pi));
    printf("sinpi(0.5) = %f, sin(pi/2) = %f\n", sinpi(0.5), sin(pi / 2));
    printf("sinpi(-0.75) = %f, sin(-3*pi/4) = %f\n", sinpi(-0.75), sin(-3 * pi / 4));
 
    // special values
    printf("sinpi(+0) = %f\n", sinpi(0.0));
    printf("sinpi(-0) = %f\n", sinpi(-0.0));
 
    // error handling
    feclearexcept(FE_ALL_EXCEPT);
    printf("sinpi(INFINITY) = %f\n", sinpi(INFINITY));
    if (fetestexcept(FE_INVALID))
        puts("    FE_INVALID raised");
}

Possible output:

sinpi(1) = 0.000000, sin(pi) = 0.000000
sinpi(0.5) = 1.000000, sin(pi/2) = 1.000000
sinpi(-0.75) = -0.707107, sin(-3*pi/4) = -0.707107
sinpi(+0) = 0.000000
sinpi(-0) = -0.000000
sinpi(INFINITY) = -nan
    FE_INVALID raised

[edit] References

  • C23 standard (ISO/IEC 9899:2023):
  • 7.12.4.13 The sinpi functions (p: 247-248)
  • 7.27 Type generic math <tgmath.h> (p: 387)

[edit] See also

(C99)(C99)
computes sine (sin(x))
(function) [edit]