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# wqqplot

## PURPOSE

Plot empirical quantile of X vs empirical quantile of Y

## SYNOPSIS

h=wqqplot(x,y,ps);

## DESCRIPTION

``` WQQPLOT   Plot empirical quantile of X vs empirical quantile of Y

CALL:  h = wqqplot(x,y,ps)

h   = handle to the plotted figure
x,y = data
ps  = plot symbol (default '+')

If two distributions are the same (or possibly linearly
transformed) the points should form an approximately straight
line.

Example:
R1=wgumbrnd(1,0,[],1,100);
R2=wgumbrnd(2,2,[],1,100);
wqqplot(R1,R2)

## CROSS-REFERENCE INFORMATION

This function calls:
 wquantile Empirical quantile (percentile). error Display message and abort function. plot Linear plot. xlabel X-axis label. ylabel Y-axis label.
This function is called by:
 cmat2extralc Extrapolate level crossing spectrum distplot Displays a 1D distribution probability plot.

## SOURCE CODE

```001 function h=wqqplot(x,y,ps);
002 %WQQPLOT   Plot empirical quantile of X vs empirical quantile of Y
003 %
004 % CALL:  h = wqqplot(x,y,ps)
005 %
006 %  h   = handle to the plotted figure
007 %  x,y = data
008 %  ps  = plot symbol (default '+')
009 %
010 % If two distributions are the same (or possibly linearly
011 % transformed) the points should form an approximately straight
012 % line.
013 %
014 % Example:
015 %   R1=wgumbrnd(1,0,[],1,100);
016 %   R2=wgumbrnd(2,2,[],1,100);
017 %   wqqplot(R1,R2)
018 %
020
021 % testen on: matlab 5.3
022 % History:
023 % revised pab 24.10.2000
025 % updated header to comform to wafo style
026 error(nargchk(2,3,nargin))
027 if nargin<3, ps = '+'; end
028 x = sort(x);
029 y = sort(y);
030 if length(x) < length(y)
031    n = length(x);
032    h=plot(x, wquantile(y, ((1:n)-0.5)/n, 1), ps);
033 elseif length(y) < length(x)
034    n = length(y);
035    h=plot(wquantile(x, ((1:n)-0.5)/n, 1), y, ps);
036 else
037    h=plot(x,y,ps);
038 end
039 xlabel('Data X')
040 ylabel('Data Y')
041```

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

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