Class Erf

java.lang.Object
org.apache.commons.math.special.Erf

public class Erf extends Object
This is a utility class that provides computation methods related to the error functions.
Version:
$Revision: 1054186 $ $Date: 2011-01-01 03:28:46 +0100 (sam. 01 janv. 2011) $
  • Method Details

    • erf

      public static double erf(double x) throws MathException

      Returns the error function

      erf(x) = 2/√π 0x e-t2dt

      This implementation computes erf(x) using the regularized gamma function, following Erf, equation (3)

      The value returned is always between -1 and 1 (inclusive). If abs(x) > 40, then erf(x) is indistinguishable from either 1 or -1 as a double, so the appropriate extreme value is returned.

      Parameters:
      x - the value.
      Returns:
      the error function erf(x)
      Throws:
      MathException - if the algorithm fails to converge.
      See Also:
    • erfc

      public static double erfc(double x) throws MathException

      Returns the complementary error function

      erfc(x) = 2/√π x e-t2dt
      = 1 - erf(x)

      This implementation computes erfc(x) using the regularized gamma function, following Erf, equation (3).

      The value returned is always between 0 and 2 (inclusive). If abs(x) > 40, then erf(x) is indistinguishable from either 0 or 2 as a double, so the appropriate extreme value is returned.

      Parameters:
      x - the value
      Returns:
      the complementary error function erfc(x)
      Throws:
      MathException - if the algorithm fails to converge
      Since:
      2.2
      See Also: