Intel® Fortran Compiler 16.0 User and Reference Guide
Inquiry Intrinsic Function (Generic): Returns a positive model number that is almost negligible compared to unity in the model representing real numbers.
result = EPSILON (x)
x |
(Input) Must be of type real; it can be scalar or array valued. |
The result is a scalar of the same type and kind parameters as x. The result has the value b 1-p. Parameters b and p are defined in Model for Real Data.
EPSILON makes it easy to select a delta for algorithms (such as root locators) that search until the calculation is within delta of an estimate. If delta is too small (smaller than the decimal resolution of the data type), the algorithm might never halt. By scaling the value returned by EPSILON to the estimate, you obtain a delta that ensures search termination.
If x is of type REAL(4), EPSILON (X) has the value 2 -23.