This version of this document is no longer maintained. For the latest documentation, see http://www.qnx.com/developers/docs. |
Log(1+x)
#include <math.h> double log1p ( double x ); float log1pf ( float x );
libm
Use the -l m option to qcc to link against this library.
The log1p() and log1pf() functions compute the value of log(1+x), where x > -1.0.
If: | log1p() returns: |
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x = NAN | NAN |
x < -1.0 | -HUGE_VAL, or NAN (errno is set to EDOM). |
x = -1.0 | -HUGE_VAL (errno may be set to ERANGE). |
If an error occurs, these functions return 0, but this is also a valid mathematical result. If you want to check for errors, set errno to 0, call the function, and then check errno again. These functions don't change errno if no errors occurred. |
Safety: | |
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Cancellation point | No |
Interrupt handler | No |
Signal handler | No |
Thread | Yes |
ilogb(), log(), logb(), log10()