inverf

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Description

Inverse error function

Arguments and Return Values

Arguments: One numeric array, with all elements between -1 and 1 (exclusive)

Return Value: An array with the same organization as the input containing the value of the inverse error function evaluated at the each element of the input. The output format is double if the input is double, float otherwise.

The inverse error function is defined as inverf(y) = x iff y = erf(x)

This function does its computations by converting the input values and evaluating them with the inverse normal function, invnorm, which has a relative error of less than 1.2e-9 (in double precision).

inverf(y) = invnorm((y+1)/2)/√2

Return format is double if input is double; float otherwise.

If no arguments are input, inverf() prints its description, as shown below.

Usage

Syntax: erf(y)

'y' - A numeric array of any format

Examples

dv> inverf()

Inverse error function
x = inverf(y) iff y = erf(x)
This function uses the inverse normal function
inverf(y) = invnorm((y + 1)/2)/sqrt(2)
Input must be y such that -1 < y < 1
Relative errors (in double precision) are less than 1.2e-9
Matches input format
Works for arrays
S.Marshall 02-22-2008

0
dv> inverf(-0.5//0.//0.5)
3x1x1 array of float, bsq format [12 bytes]
-0.476936       0.00000 0.476936
dv> inverf(1)

Input must be y such that -1 < y < 1

0

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Major Sub-Functions

Related Functions

Recent Library Changes

Created On: 02-22-2008
Modified On: 02-25-2008

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