HP-UX Reference (11i v1 05/09) - 3 Library Functions N-Z (vol 7)

scalbn(3M) scalbn(3M)

NAME

scalbn() - scale exponent of a radix-independent ﬂoating-point number

SYNOPSIS

#include <math.h>

double scalbn(double x, int n);

DESCRIPTION

The scalbn() function returns x ∗ r

, where r is the radix of the machine’s ﬂoating-point arithmetic.

When r is 2 (as it is on all PA-RISC systems),

scalbn() is equivalent to ldexp().

The

scalb() function is recommended by the IEEE-754 standard for ﬂoating-point arithmetic. The

ISO/ANSI C committee has approved the

scalbn() function for inclusion in the C9X draft standard.

To use this function, compile either with the default

-Ae option or with the -Aa and -D_HPUX_SOURCE

options. Make sure your program includes <

math.h>. Link in the math library by specifying -lm on the

compiler or linker command line.

RETURN VALUE

Upon successful completion, the

scalbn() function returns x ∗ r

scalbn(-x, n) and -scalbn(x, n) are equivalent.

If x is ±INFINITY, zero, or a NaN,

scalbn() returns x.

If the correct value after rounding would be smaller in magnitude than

MINDOUBLE, scalbn() returns

zero.

If the correct value would overﬂow,

scalbn() returns ±INFINITY (according to the sign of x).

ERRORS

No errors are deﬁned.