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# berk2prob

## PURPOSE

BERK2PROB convert Berksons to probability

## SYNOPSIS

function [p,d]=berk2prob(b)

## DESCRIPTION

```BERK2PROB convert Berksons to probability

Inputs:  B(M,N)       matrix containing Berkson values

Outputs:  P(M,N)       Corresponding probability values
D(M,N)       Corresponding derivatives dP/dB

Berksons, or log-odds, are a nonlinear scale for measuring
probability defined by B = log2(P./(1-P)).
When Berksons are used to measure probability, a logistic
psychometric function becomes linear.

The inverse function is berk2prob()```

## CROSS-REFERENCE INFORMATION

This function calls:
This function is called by:

## SOURCE CODE

```0001 function [p,d]=berk2prob(b)
0002 %BERK2PROB convert Berksons to probability
0003 %
0004 %  Inputs:  B(M,N)       matrix containing Berkson values
0005 %
0006 % Outputs:  P(M,N)       Corresponding probability values
0007 %           D(M,N)       Corresponding derivatives dP/dB
0008 %
0009 % Berksons, or log-odds, are a nonlinear scale for measuring
0010 % probability defined by B = log2(P./(1-P)).
0011 % When Berksons are used to measure probability, a logistic
0012 % psychometric function becomes linear.
0013 %
0014 % The inverse function is berk2prob()
0015
0016 %      Copyright (C) Mike Brookes 2014
0017 %      Version: \$Id: berk2prob.m 4501 2014-04-24 06:28:21Z dmb \$
0018 %
0019 %   VOICEBOX is a MATLAB toolbox for speech processing.
0021 %
0022 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0023 %   This program is free software; you can redistribute it and/or modify
0025 %   the Free Software Foundation; either version 2 of the License, or
0026 %   (at your option) any later version.
0027 %
0028 %   This program is distributed in the hope that it will be useful,
0029 %   but WITHOUT ANY WARRANTY; without even the implied warranty of
0030 %   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
0031 %   GNU General Public License for more details.
0032 %
0033 %   You can obtain a copy of the GNU General Public License from
0034 %   http://www.gnu.org/copyleft/gpl.html or by writing to
0035 %   Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA.
0036 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
0037 p=1-1./(1+pow2(b));
0038 if nargout>1
0039     d=log(2)*p.*(1-p);
0040 end```

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