SIGFPUFL

SIGFPUFL

Floating-Point Underflow

Default handling
Ignoring the signal
Information returned by siginfo
Notes on defining a handler

The SIGFPUFL signal is raised when the magnitude of the nonzero result of a floating-point computation is smaller than the smallest nonzero floating-point value supported by the hardware and default handling is in effect for SIGFPE . If you specified a handler for SIGFPE (either SIG_IGN or a function you define), SIGFPUFL is not raised.

Default handling

If the SIGFPUFL signal is raised and default handling is in effect, the result of the computation that raised the signal is set to 0 and execution continues normally.

Ignoring the signal

If your program ignores SIGFPUFL , program execution continues, and the result of the computation that raised the signal is set to 0.

Information returned by siginfo

If you call siginfo after a SIGFPUFL signal occurs, siginfo returns a pointer to a structure of type FPE_t . Refer to the description of SIGFPE for a discussion of this structure.

Notes on defining a handler

If you define a handler for SIGFPUFL , you can change the result of the computation by using the information returned by siginfo . Refer to the example in the description of the siginfo function for an illustration of this technique.

Note: If a handler defined for SIGFPUFL does not change the value of the result, the result of the computation is undefined and it is not automatically set to 0. [cautionend]

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