1: #include <petscsys.h>
3: /*@C
4: PetscIsCloseAtTol - Returns whether the two floating point numbers
5: are close at a given relative and absolute tolerances.
7: Input Parameters:
8: + a - first floating point number
9: . b - second floating point number
10: . rtol - relative tolerance
11: - atol - absolute tolerances
13: Reference:
14: . * - https://www.python.org/dev/peps/pep-0485/
16: Level: beginner
18: .seealso: `PetscEqualReal()`, `PetscEqualScalar()`
19: @*/
20: PetscBool PetscIsCloseAtTol(PetscReal a, PetscReal b, PetscReal rtol, PetscReal atol)
21: {
22: PetscReal diff;
23: /* NaN is not considered close to any other value, including NaN */
24: if (PetscIsNanReal(a) || PetscIsNanReal(b)) return PETSC_FALSE;
25: /* Fast path for exact equality or two infinities of same sign */
26: if (a == b) return PETSC_TRUE;
27: /* Handle two infinities of opposite sign */
28: if (PetscIsInfReal(a) || PetscIsInfReal(b)) return PETSC_FALSE;
29: /* Cannot error if tolerances are negative */
30: rtol = PetscAbsReal(rtol);
31: atol = PetscAbsReal(atol);
32: /* The regular check for difference within tolerances */
33: diff = PetscAbsReal(b - a);
34: return ((diff <= PetscAbsReal(rtol * b)) || (diff <= PetscAbsReal(rtol * a)) || (diff <= atol)) ? PETSC_TRUE : PETSC_FALSE;
35: }