scalbn(3) - NetBSD Manual Pages

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SCALBN(3)               NetBSD Library Functions Manual              SCALBN(3)


NAME

     scalbn, scalbnf, scalbnl -- exponent using FLT_RADIX


LIBRARY

     Math Library (libm, -lm)


SYNOPSIS

     #include <math.h>

     double
     scalbn(double x, int n);

     float
     scalbnf(float x, int n);

     long double
     scalbnl(long double x, int n);


DESCRIPTION

     The scalbn(), scalbnf(), and scalbnl() functions compute x * r^n, where r
     is the radix of the machine's floating point arithmetic, defined by the
     FLT_RADIX constant in <float.h>.  The rationale is efficiency; r^n is not
     computed explicitly.


RETURN VALUES

     As described above, upon successful completion, the described functions
     return the exponent computed using FLT_RADIX.  Otherwise the following
     may occur:

           1.   When the result would cause an overflow, a range error occurs
                and ±HUGE_VAL, ±HUGE_VALF, or ±HUGE_VALL is returned according
                to the sign of x and the return type of the corresponding
                function.

           2.   When the correct value would cause an underflow and it is not
                representable, a range error occurs and either 0.0 or an
                implementation-defined value is returned.  When an underflow
                occurs but the correct value is representable, a range error
                occurs but the correct value is returned.

           3.   If x is ±0 or ±Inf, x is returned.  Likewise, if n is zero, x
                is returned.  If x is NaN, NaN is returned.


SEE ALSO

     exp(3), frexp(3), ldexp(3), math(3)


STANDARDS

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

NetBSD 6.0                    September 18, 2011                    NetBSD 6.0