scalbn, scalbnf, scalbnl, scalbln, scalblnf, scalblnl
Multiplies a floating-point number by an integral power of FLT_RADIX.
double scalbn(
double x,
int exp
);
float scalbn(
float x,
int exp
); // C++ only
long double scalbn(
long double x,
int exp
); // C++ only
float scalbnf(
float x,
int exp
);
long double scalbnl(
long double x,
int exp
);
double scalbln(
double x,
long exp
);
float scalbln(
float x,
long exp
); // C++ only
long double scalbln(
long double x,
long exp
); // C++ only
float scalblnf(
float x,
long exp
);
long double scalblnl(
long double x,
long exp
);
Parameters
x
Floating-point value.exp
Integer exponent.
Return Value
The scalbn functions return the value of x * FLT_RADIXexp when successful. On overflow (depending on the sign of x), scalbn returns +/– HUGE_VAL; the errno value is set to ERANGE.
For more information about errno and possible error return values, see errno, _doserrno, _sys_errlist, and _sys_nerr.
Remarks
FLT_RADIX is defined in <float.h> as the native floating-point radix; on binary systems, it has a value of 2, and scalbn is equivalent to ldexp.
Because C++ allows overloading, you can call overloads of scalbn and scalbln that take and return float or long double types. In a C program, scalbn always takes a double and an int and returns a double, and scalbln always takes a double and a long and returns a double.
Requirements
Function |
C header |
C++ header |
|---|---|---|
scalbn, scalbnf, scalbnl, scalbln, scalblnf, scalblnl |
<math.h> |
<cmath> |
For additional compatibility information, see Compatibility.
Example
// crt_scalbn.c
// Compile using: cl /W4 crt_scalbn.c
#include <math.h>
#include <stdio.h>
int main( void )
{
double x = 6.4, y;
int p = 3;
y = scalbn( x, p );
printf( "%2.1f times FLT_RADIX to the power of %d is %2.1f\n", x, p, y );
}
Output
6.4 times FLT_RADIX to the power of 3 is 51.2