nonduplicate

Makes all values of input array distinct - used to get interp1 to work when x data has duplicates.

% function xout = nonduplicate(xin)
%
% written so that interp1 doesn't return error:
% 'The values of X should be distinct.'
%
% does not sort data
% checks for duplicate values in xin
% returns xout where all values are distinct
%
% if duplicates found, separates values by small value (eps)
%
% input xin must be 1D
%
% useage:
% x = nonduplicate(x);
%
% yi = interp1(nonduplicate(x),y,xi)
%
% Example:
% interp1([1,1,2],[1,1,2],1.5)
% returns an error.
%
% interp1(nonduplicate([1,1,2]),[1,1,2],1.5)
% works just fine.
%
% written by Nathan Tomlin, [e-mail]
% v2: update 190321 after tip from Natalia Aziares Aguayo <[e-mail]>
% same as listed here: https://stackoverflow.com/questions/13407030/desort-a-vector-undo-a-sorting
%
% should probably use consolidator instead