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Multiply a floating-point number by an integral power of 2
#include <math.h>
double ldexp( double x,
int exp );
float ldexp( float x,
int exp );
- x
- A floating-point number.
- exp
- The exponent of 2 to multiply x by.
libm
Use the -l m option to
qcc
to link against this library.
These functions multiply the floating-point number
x by
2exp.
A range error may occur.
x × 2exp
|
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. |
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
int main( void )
{
double value;
value = ldexp( 4.7072345, 5 );
printf( "%f\n", value );
return EXIT_SUCCESS;
}
produces the output:
150.631504
ANSI,
POSIX 1003.1
Safety: | |
Cancellation point |
No |
Interrupt handler |
No |
Signal handler |
No |
Thread |
Yes |
frexp(),
modf()
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