1b10005b4SLisandro Dalcin #include <petscsys.h> 2b10005b4SLisandro Dalcin 3b10005b4SLisandro Dalcin /*@C 4667f096bSBarry Smith PetscIsCloseAtTol - Returns whether the two `PetscReal` numbers 5*1d27aa22SBarry Smith are close at a given relative and absolute tolerances <https://www.python.org/dev/peps/pep-0485/>. 6b10005b4SLisandro Dalcin 7d8d19677SJose E. Roman Input Parameters: 8b10005b4SLisandro Dalcin + a - first floating point number 9b10005b4SLisandro Dalcin . b - second floating point number 10b10005b4SLisandro Dalcin . rtol - relative tolerance 11a2b725a8SWilliam Gropp - atol - absolute tolerances 12b10005b4SLisandro Dalcin 13667f096bSBarry Smith Level: beginner 14667f096bSBarry Smith 1528dd6638SJacob Faibussowitsch .seealso: `PetscIsCloseAtTolScalar()`, `PetscEqualReal()`, `PetscEqualScalar()` 16b10005b4SLisandro Dalcin @*/ PetscIsCloseAtTol(PetscReal a,PetscReal b,PetscReal rtol,PetscReal atol)17d71ae5a4SJacob FaibussowitschPetscBool PetscIsCloseAtTol(PetscReal a, PetscReal b, PetscReal rtol, PetscReal atol) 18d71ae5a4SJacob Faibussowitsch { 19b10005b4SLisandro Dalcin PetscReal diff; 20b10005b4SLisandro Dalcin /* NaN is not considered close to any other value, including NaN */ 21b10005b4SLisandro Dalcin if (PetscIsNanReal(a) || PetscIsNanReal(b)) return PETSC_FALSE; 22b10005b4SLisandro Dalcin /* Fast path for exact equality or two infinities of same sign */ 23b10005b4SLisandro Dalcin if (a == b) return PETSC_TRUE; 24b10005b4SLisandro Dalcin /* Handle two infinities of opposite sign */ 25b10005b4SLisandro Dalcin if (PetscIsInfReal(a) || PetscIsInfReal(b)) return PETSC_FALSE; 26b10005b4SLisandro Dalcin /* Cannot error if tolerances are negative */ 279371c9d4SSatish Balay rtol = PetscAbsReal(rtol); 289371c9d4SSatish Balay atol = PetscAbsReal(atol); 29b10005b4SLisandro Dalcin /* The regular check for difference within tolerances */ 30b10005b4SLisandro Dalcin diff = PetscAbsReal(b - a); 31b10005b4SLisandro Dalcin return ((diff <= PetscAbsReal(rtol * b)) || (diff <= PetscAbsReal(rtol * a)) || (diff <= atol)) ? PETSC_TRUE : PETSC_FALSE; 32b10005b4SLisandro Dalcin } 33