#define _GNU_SOURCE #include /* fedisableexcept() */ #include /* DBL_MIN */ #include /* assert() */ #include /* isinf() */ void test_overflow(void) { /* FE_OVERFLOW: The overflow exception occurs when a result has to be represented as a floating-point number, but has (much) larger absolute value than the largest (finite) floating-point number that is representable. */ volatile double x = DBL_MAX; volatile double y = (x + x); assert(isinf(y)); assert(copysign(1.0, y) == 1.0); } void test_underflow(void) { /* FE_UNDERFLOW: The underflow exception occurs when a result has to be represented as a floating-point number, but has smaller absolute value than the smallest positive normalized floating-point number (and would lose much accuracy when represented as a denormalized number). Note: DBL_MIN is the normalized minimum. */ volatile double x = DBL_MIN; volatile double y = (x * x); assert(y == 0.0); } void test_invalid(void) { /* FE_INVALID: the invalid exception occurs when there is no well-defined result for an operation, as for 0/0 or infinity - infinity, or sqrt(-1). */ volatile double x = 0.0; volatile double y = x / x; assert(isnan(y)); } int main() { #if 0 feenableexcept(FE_OVERFLOW); #else fedisableexcept(FE_OVERFLOW); #endif #if 0 feenableexcept(FE_UNDERFLOW); #else fedisableexcept(FE_UNDERFLOW); #endif #if 0 feenableexcept(FE_INVALID); #else fedisableexcept(FE_INVALID); #endif test_overflow(); test_underflow(); test_invalid(); return 0; }