c/numeric/fenv/feenv

1) Attempts to store the status of the floating-point environment in the object pointed to by.

2) Attempts to establish the floating-point environment from the object pointed to by . The value of that object must be previously obtained by a call to feholdexcept or or be a floating-point macro constant. If any of the floating-point status flags are set in, they become set in the environment (and are then testable with fetestexcept), but the corresponding floating-point exceptions are not raised (execution continues uninterrupted)

Return value
on success, non-zero otherwise.