remainder(3) - NetBSD Manual Pages

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REMAINDER(3)            NetBSD Library Functions Manual           REMAINDER(3)


NAME

     remainder, remainderf, remquo, remquof -- remainder functions


LIBRARY

     Math Library (libm, -lm)


SYNOPSIS

     #include <math.h>

     double
     remainder(double x, double y);

     float
     remainderf(float x, float y);

     double
     remquo(double x, double y, int *quo);

     float
     remquof(float x, float y, int *quo);


DESCRIPTION

     Provided that y != 0 , the remainder() and remainderf() functions calcu-
     late the floating-point remainder r of

           r = x - ny,

     where n is the integral value nearest to the exact value of x / y.  If

           | n - x / y | = 1/2 ,

     the value n is chosen to be even.  Consequently, the remainder is com-
     puted exactly and | r | <= | y | / 2 .

     Also the remquo() and remquof() functions calculate the remainder as
     described above.  But these additionally use quo to store a value whose
     sign is the sign of x / y and whose magnitude is congruent modulo 2^k to
     the magnitude of the integral quotient of x / y, where k is an implemen-
     tation-defined integer greater than or equal to 3.

     The rationale of the remquo() family of functions relates to situations
     where only few bits of the quotient are required.  The exact representa-
     tion of the quotient may not be meaningful when x is large in magnitude
     compared to y.


RETURN VALUES

     The functions return the remainder independent of the rounding mode.  If
     y is zero , NaN is returned and a domain error occurs.  A domain error
     occurs and a NaN is returned also when x is infinite but y is not a NaN.
     If either x or y is NaN, a NaN is always returned.


SEE ALSO

     div(3), fast_remainder32(3), fmod(3), math(3)


STANDARDS

     The described functions conform to ISO/IEC 9899:1999 (``ISO C99'').

NetBSD 6.0.1                  September 18, 2011                  NetBSD 6.0.1