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logb

Computes the exponent of `x`

, which is the integral part of logr |`x`

|, as a signed floating-point value, for non-zero `x`

, where `r`

is the radix of the machine's floating-point arithmetic, which is the value of FLT_RADIX defined in the <float.h> header.

If `x`

is subnormal it is treated as though it were normalized; thus for finite positive `x`

:

1 <= x * FLT_RADIX-logb(x) < FLT_RADIX

#include <math.h> double logb (double x);

Upon successful completion, these functions shall return the exponent of `x`

.

If `x`

is +/-0, a pole error shall occur and logb() shall return -HUGE_VAL.

If `x`

is NaN, a NaN shall be returned.

If `x`

is +/-Inf, +Inf shall be returned.

Versions | Defined in | Include | Link to |
---|---|---|---|

INtime 3.0 | intime/rt/include/math.h | math.h | clib.lib |