scalbn, scalbnf, scalbnl, scalbln, scalblnf, scalblnl

 

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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.

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.

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.

FunctionC headerC++ header
scalbn, scalbnf, scalbnl, scalbln, scalblnf, scalblnl<math.h><cmath>

For additional compatibility information, see Compatibility.

// 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 );  
}  

6.4 times FLT_RADIX to the power of 3 is 51.2  

System::Math::Pow

Floating-Point Support
frexp
ldexp
modf, modff, modfl

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