1 static char help[] = "Tests not trapping an underflow\n\n"; 2 3 #include <petscsys.h> 4 #include <float.h> 5 #include <math.h> 6 7 /* From https://stackoverflow.com/questions/37193363/float-underflow-in-c-explanation */ 8 void demo(void) 9 { 10 /* 11 FLT_MIN, FLT_MIN and the display of the floating point numbers are not portable 12 13 const char *format = "%.10e %a\n"; 14 printf(format, FLT_MIN, FLT_MIN); 15 printf(format, FLT_TRUE_MIN, FLT_TRUE_MIN); 16 */ 17 18 float f = nextafterf(1.0f, 2.0f); 19 do { 20 /* if trapping of underflow is turned on then this will generate an exception */ 21 f /= 2; 22 /* printf(format, f, f); */ 23 } while (f); 24 } 25 26 int main(int argc, char **argv) 27 { 28 PetscFunctionBeginUser; 29 PetscCall(PetscInitialize(&argc, &argv, NULL, help)); 30 demo(); 31 PetscCall(PetscFinalize()); 32 return 0; 33 } 34 35 /*TEST 36 37 test: 38 TODO: Doesn't work on AArch64 targets. There's a known hardware limitation. arch-ci-linux-cmplx-single 39 args: -fp_trap 40 41 TEST*/ 42