3.4.1 ieee_functions(3m) and ieee_sun(3m)

The functions described by ieee_functions(3m) and ieee_sun(3m) provide capabilities either required by the IEEE standard or recommended in its appendix. These are implemented as efficient bit mask operations.

Table 3-5  ieee_functions(3m)

Function Description math.h Header file copysign(x,y) x with y's sign bit fabs(x) Absolute value of x fmod(x, y) Remainder of x with respect to y ilogb(x) Base 2 unbiased exponent of x in integer format nextafter(x,y) Next representable number after x, in the direction y remainder(x,y) Remainder of x with respect to y scalbn(x,n) x × 2n

Table 3-6  ieee_sun(3m)

Function Description sunmath.h Header file fp_class(x) Classification function isinf(x) Classification function isnormal(x) Classification function issubnormal(x) Classification function iszero(x) Classification function signbit(x) Classification function nonstandard_arithmetic(void) Enable nonstandard mode standard_arithmetic(void) Enable standard mode ieee_retrospective(*f) n/a

The remainder(x,y) is the operation specified in IEEE Standard 754-1985. The difference between remainder(x,y) and fmod(x,y) is that the sign of the result returned by remainder(x,y) might not agree with the sign of either x or y, whereas fmod(x,y) always returns a result whose sign agrees with x. Both functions return exact results and do not generate inexact exceptions.

Table 3-7  Calling ieee_functions From Fortran

IEEE Function Single Precision Double Precision Quadruple Precision copysign(x,y) t=r_copysign(x,y) z=d_copysign(x,y) z=q_copysign(x,y) ilogb(x) i=ir_ilogb(x) i=id_ilogb(x) i=iq_ilogb(x) nextafter(x,y) t=r_nextafter(x,y) z=d_nextafter(x,y) z=q_nextafter(x,y) scalbn(x,n) t=r_scalbn(x,n) z=d_scalbn(x,n) z=q_scalbn(x,n) signbit(x) i=ir_signbit(x) i=id_signbit(x) i=iq_signbit(x)

Table 3-8  Calling ieee_sun From Fortran

IEEE Function Single Precision Double Precision Quadruple Precision signbit(x) i=ir_signbit(x) i=id_signbit(x) i=iq_signbit(x)