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# cmat2amp

## PURPOSE

Calculates a histogram of amplitudes from a cycle matrix.

## SYNOPSIS

amp_hist = cmat2amp(param,F)

## DESCRIPTION

``` CMAT2AMP Calculates a histogram of amplitudes from a cycle matrix.

CALL:  amp_hist = cmat2amp(param,F);

amp_hist = a two column matrix with amplitudes (defined by  param)
in the first column and frequencies in the second.
param    = the parameter matrix.
F        = the  nxn  frequency matrix for the cycle count.

Example:
[dtp,u,tp] = dat2dtp([-2 2 32],x,0.2); % Discrete TP & rainflow filter 0.2
RFM = dtp2rfm(dtp,32);                 % Calculate rainflow matrix
amp_hist = cmat2amp([-2 2 32],RFM);    % Get amplitude histigram
bar(amp_hist(:,1),amp_hist(:,2))       % Plot histogram

## CROSS-REFERENCE INFORMATION

This function calls:
 levels Calculates discrete levels given the parameter matrix. error Display message and abort function.
This function is called by:
 cmat2dam Calculates the total Palmgren-Miner damage of a cycle matrix. rfmextrapolate Extrapolates a rainflow matrix. test_cycles Quick test of the routines in module 'cycles'

## SOURCE CODE

```001 function amp_hist = cmat2amp(param,F)
002 %CMAT2AMP Calculates a histogram of amplitudes from a cycle matrix.
003 %
004 % CALL:  amp_hist = cmat2amp(param,F);
005 %
006 %   amp_hist = a two column matrix with amplitudes (defined by  param)
007 %              in the first column and frequencies in the second.
008 %   param    = the parameter matrix.
009 %   F        = the  nxn  frequency matrix for the cycle count.
010 %
011 % Example:
012 %   x = load('sea.dat');                   % Load data
013 %   [dtp,u,tp] = dat2dtp([-2 2 32],x,0.2); % Discrete TP & rainflow filter 0.2
014 %   RFM = dtp2rfm(dtp,32);                 % Calculate rainflow matrix
015 %   amp_hist = cmat2amp([-2 2 32],RFM);    % Get amplitude histigram
016 %   bar(amp_hist(:,1),amp_hist(:,2))       % Plot histogram
017 %
019
020 % Tested  on Matlab  5.3
021 %
022 % History:
023 % Created by PJ (Pär Johannesson) 03-Nov-1999
024
025 % Check input arguments
026
027 ni = nargin;
028 no = nargout;
029 error(nargchk(2,2,ni));
030
031 n=param(3); % Number of discrete levels
032
033 amp_hist=zeros(n,2);
034
035
036 % First column: The values of the amplitudes
037 amp_hist(:,1) = levels([0 param(2)-param(1) n])'/2;
038
039 % Second  column: The number of amplitudes
040 for i=0:n-1
041   amp_hist(i+1,2)=sum(diag(F,i));
042 end
043```

Mathematical Statistics
Centre for Mathematical Sciences
Lund University with Lund Institute of Technology

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