﻿ Problem Descriptor Reference > The Elements of a Descriptor > Built-in Functions > Analytic Functions

Analytic Functions   The following analytic functions are supported by FlexPDE:

 Function Comments ABS(x) Absolute value ARCCOS(x) Inverse cosine (returns radians) ARCSIN(x) Inverse sine (returns radians) ARCTAN(x) Inverse tangent (returns radians) ATAN2(y,x) Arctan(y/x) with numerically safe implementation* ATAN2V6(y,x) Arctan(y/x) with numerically safe implementation* BESSI(order,x) Modified Bessel function I for real x BESSJ(order,x) Bessel Function J BESSK(order,x) Modified Bessel function K for real x BESSY(order,x) Bessel Function Y COS(x) cosine of x (angle in radians)** COSH(x) Hyperbolic cosine ERF(x) Error Function ERFC(x) Complementary Error Function EXP(x) Exponential function EXPINT(x) Exponential Integral Ei(x) for real x>0 *** EXPINT(n,x) Exponential Integral En(x) for n>=0, real x>0 *** GAMMAF(x) Gamma function for real x>0 GAMMAF(a,x) Incomplete gamma function for real a>0, x>0 LOG10(x) Base-10 logarithm LN(x) Natural logarithm SIN(x) sine of x (angle in radians)** SINH(x) Hyperbolic sine SQRT(x) Square Root TAN(x) tangent of x (angle in radians)** TANH(x) Hyperbolic tangent

*  Note that in version 7 the definition has changed to use the standard range of -π to π.  ATAN2V6 is provided for compatibility with old behavior.

**  Use for example COS(x DEGREES) to convert arguments to radians.

*** as defined in Abramowitz & Stegun, "Handbook of Mathematical Functions".

Examples:

Samples | Usage | Functions | Standard_Functions.pde