scalb()
Load the exponent of a radix-independent floating point number
Synopsis:
#include <math.h> double scalb( double x, double n );
Arguments:
- x
- The floating point number that you want to multiply by the exponent.
- n
- The exponent to apply to the radix of the machine's floating-point arithmetic.
Description:
These functions compute x × rn, where r is the radix of the machine's floating point arithmetic and n is a finite number. When r is 2, scalb() is equivalent to ldexp().
We recommend that you use
scalbn()
because it computes by manipulating exponents, instead of using mock
multiplications or additions.
Returns:
x × rn
If an error occurs, these functions return 0, but this is also a valid
mathematical result.
If you want to check for errors, set
errno
to 0, call the function, and then check errno again.
These functions don't change errno if no errors occurred.
Examples:
#include <stdio.h>
#include <errno.h>
#include <inttypes.h>
#include <math.h>
#include <fpstatus.h>
int main(int argc, char** argv)
{
double a, b, c, d;
a = 10;
b = 2;
c = scalb(a, b);
d = sqrt(c/a);
printf("Radix of machines fp arithmetic is %f \n", d);
printf("So %f = %f * (%f ^ %f) \n", c, a, d, b);
return(0);
}
produces the output:
Radix of machines fp arithmetic is 2.000000 So 40.000000 = 10.000000 * (2.000000 ^ 2.000000)
Classification:
| Safety: | |
|---|---|
| Cancellation point | No |
| Interrupt handler | No |
| Signal handler | No |
| Thread | Yes |