# FINDING INVERSE ERROR FUNCTION

In a previous blog at autarkaw.wordpress.com (August 24, 2010), we set up a nonlinear equation to find the inverse error function. In this blog, we will solve this equation. The problem is given at and we are solving Exercise 1 of the pdf file.

## TOPIC

Finding inverse error function

## SUMMARY

```% Language : Matlab 2010a;
% Authors : Autar Kaw;
% Mfile available at
% http://numericalmethods.eng.usf.edu/blog/inverse_erf_matlab.m;
% Last Revised : August 27, 2010
% Abstract: This program shows you how to find the inverse error function
clc
clear all
```

## INTRODUCTION

```disp('ABSTRACT')
disp('   This program shows you how to')
disp('   find the inverse error function')
disp(' ')
disp('AUTHOR')
disp('   Autar K Kaw of http://autarkaw.wordpress.com')
disp(' ')
disp('MFILE SOURCE')
disp('   http://numericalmethods.eng.usf.edu/blog/inverse_erf_matlab.m')
disp('  ')
disp('PROBLEM STATEMENT')
disp('   http://numericalmethods.eng.usf.edu/blog/inverseerror.pdf')
disp('        Exercise 1')
disp(' ')
disp('LAST REVISED')
disp('   August 27, 2010')
disp(' ')
```
```ABSTRACT
This program shows you how to
find the inverse error function

AUTHOR
Autar K Kaw of http://autarkaw.wordpress.com

MFILE SOURCE
http://numericalmethods.eng.usf.edu/blog/inverse_erf_matlab.m

PROBLEM STATEMENT
http://numericalmethods.eng.usf.edu/blog/inverseerror.pdf
Exercise 1

LAST REVISED
August 27, 2010

```

## INPUTS

Value of error function

```erfx=0.5;
```

## DISPLAYING INPUTS

```disp('INPUTS')
fprintf(' The value of error function= %g',erfx)
disp('  ')
disp('  ')
```
```INPUTS
The value of error function= 0.5

```

## CODE

```syms t x
inverse_erf=solve(int(2/sqrt(pi)*exp(-t^2),t,0,x)-erfx);
inverse_erf=double(inverse_erf);
```

## DISPLAYING OUTPUTS

```disp('OUTPUTS')
fprintf(' Value of inverse error function from mfile is= %g',inverse_erf)
fprintf('\n Value of inverse error function using erfinv is= %g',erfinv(erfx))
disp('  ')
```
```OUTPUTS
Value of inverse error function from mfile is= 0.476936
Value of inverse error function using erfinv is= 0.476936
```