"Output argument "xxx" (and maybe others) not assigned during call" and "if statement" problem

Hello everyone.

I'm having a bit of trouble with some matlab code and was wondering could you help. I have introduced some 'if' statements into my code to pad an array with zeros. I have done this as the correlation function will not work if the arrays/vectors are of different lengths. However, since the introduction of the statements, I am getting the following error;

*Error in ==> comparescan at 3

imAx = imread('rh1ro5.bmp'); %reads in the handprint

??? Output argument "linearftAx" (and maybe others) not assigned during call to "C:\Users\Documents\MATLAB\comparescan.m>comparescan".

The code is as follows;*

    function [imAx, ftAx, linearftAx] = comparescan(varargin)

imAx = imread('rh1ro5.bmp');         %reads in the handprint
%imAn = imnoise(imA,'salt & pepper', 0.002);

BWA = rgb2gray(imAx);

BW1A = roicolor(BWA,50,500);      %creates a binary mask of the image

BW2A = bwareaopen(BW1A, 50);      %removes anything less than 50 connected pixels

BW3A = bwperim(BW2A,8);           %draws a boundary around the binary mask

imwrite(BW3A,'contour.bmp','bmp');

IA = imread('contour.bmp');

[RaA cxA cyA] = max_inscribed_circle(IA);

BWcropA = circlecrop(BWA,RaA,cxA,cyA);

BWcropA1 = BWcropA(any(BWcropA'),any(BWcropA));

[PC, or, ft, T] = phasecongmono(BWcropA1);

global ftA
global linearft

ftAx = ft;

imwrite(BWcropA1,'compare.bmp','bmp');

L1 = length(ftA);
L2 = length(ftAx);

P=(L1-L2)/2;
Q=(L2-L1)/2;

if (L2<L1);

Pad1 = padarray(ftAx,[P P]);   
linearftAx=reshape(Pad1,[],1);

return

end

if (L1<L2);

Pad2 = padarray(ftA,[Q Q]);   
linearft=reshape(Pad2,[],1);

end

I can't see what's wrong here. I understand that 'linearftAx' isn't returning a value to the output argument of the function, but I don't know why as the variable is declared in the if statement.

Answer 1

[Image Analyst]

Apparently it never gets inside the "if" statements to make the assignment. You should put

linearftAx = 0;

at the start of your function just to ensure that it has something to return.

[Garry]

Thanks Image Analyst, i'm not surprised it was you that answered me first!

I did try that already (well I just declared 'linearftAx = [];').

The error is gone alright, but as you can imagine, I just end up with an empty array instead. Have you any idea why my function isn't getting to the if statements?

[Walter Roberson]

What if the lengths were equal? You test L2<L1 and then L1<L2 but you "fall through" if L2==L1

[Garry]

no action is required if L1 and L2 are equal. although I haven't listed it here, i am using the corrcoef() function after the if statements. the padding is needed as corrcoef() won't work if the 2 arrays to be tested are of different demensions. But if L1==L2, there is no issue.

[Walter Roberson]

But you have a "return" if L2<L1 so corrcoef would not be called in that case.

[Garry]

true, i've since removed the returns and have progressed the code somewhat. thanks for your time.