Updated: April 19, 2023 |

*Load the exponent of a radix-independent floating point number*

#include <math.h> double scalbln ( doublex, long intn); float scalblnf ( floatx, long intn); long double scalblnl ( long doublex, long intn);

`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.

- libm
- The general-purpose math library.
- libm-sve
- (QNX Neutrino 7.1 or later) A library that optimizes the code for ARMv8.2 chips that have Scalable Vector Extension hardware.

Your system requirements will determine how you should work with these libraries:

- If you want only selected processes to run with the SVE version, you can include both libraries in your OS image and use the -l m or -l m-sve option to qcc to link explicitly against the appropriate one.
- If you want all processes to use the SVE version, include libm-sve.so in your OS image and set up a symbolic link from libm.so to libm-sve.so. Use the -l m option to qcc to link against the library.

Note:
Compile your program with the -fno-builtin option to prevent the compiler from using a
built-in version of the function.

The scalbln(), scalblnf(), and scalblnl() functions
compute `x` × r^{n},
where `r` is the radix of the machine's floating-point arithmetic.
The difference between the
scalbn*
and scalbln* functions is the type of the second argument.

To check for error situations, use feclearexcept() and fetestexcept(). For example:

- Call
`feclearexcept(FE_ALL_EXCEPT)`before calling scalbln(), scalblnf(), or scalblnl(). - On return, if
`fetestexcept(FE_ALL_EXCEPT)`is nonzero, then an error has occurred.

`x` × `r`^{n}

If: | These functions return: | Errors: |
---|---|---|

x is NaN |
NaN | — |

x is ±0.0 or ±Inf |
x |
— |

n is 0 |
x |
— |

The correct value would cause underflow | The correct value, after rounding | FE_UNDERFLOW |

The correct value would cause overflow | Inf | FE_OVERFLOW |

These functions raise FE_INEXACT if the FPU reports that the result can't be exactly represented as a floating-point number.

Safety: | |
---|---|

Cancellation point | No |

Interrupt handler | Yes |

Signal handler | Yes |

Thread | Yes |