##### Synopsis

    #include <math.h>
    double ldexp(double x, int exp);

##### Description

ldexp multiplies a floating-point number by an integral power of 2.

ldexp returns x * 2^exp.

##### Fast math library behavior

If the result overflows, errno is set to ERANGE and ldexp returns HUGE_VAL.

##### IEC 60559 math library behavior

If x is ? or NaN, ldexp returns x.
If the result overflows, ldexp returns ?.

##### Portability

ldexp conforms to ISO/IEC 9899:1990 (C90) and ISO/IEC 9899:1999 (C99).