Internal Functions
Xpress NonLinear provides a set of standard functions for use in formulae. Many are standard mathematical functions; there are a few which are intended for specialized applications.
The following is a list of all the Xpress NonLinear internal functions:
| ABS |
Absolute value
|
| ARCCOS |
Arc cosine trigonometric function
|
| ARCSIN |
Arc sine trigonometric function
|
| ARCTAN |
Arc tangent trigonometric function
|
| COS |
Cosine trigonometric function
|
| EXP |
Exponential function (e raised to the power)
|
| LN |
Natural logarithm
|
| LOG, LOG10 |
Logarithm to base 10
|
| MAX |
Maximum value of two items
|
| MIN |
Minimum value of two items
|
| SIN |
Sine trigonometric function
|
| SQRT |
Square root
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| TAN |
Tangent trigonometric function
|
Trigonometric functions
The trigonometric functions SIN, COS and TAN return the value corresponding to their argument in radians. SIN and COS are well-defined, continuous and differentiable for all values of their arguments; care must be exercised when using TAN because it is discontinuous.
The inverse trigonometric functions ARCSIN and ARCCOS are undefined for arguments outside the range -1 to +1 and special care is required to ensure that no attempt is made to evaluate them outside this range. Derivatives for the inverse trigonometric functions are always calculated numerically.
Other mathematical functions
Most of the mathematical functions are differentiable, although care should be taken in using analytic derivatives where the derivative is changing rapidly.