# How do I solve this particular error? First-time MATLAB user

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Blake on 12 Apr 2014
Commented: Blake on 21 Apr 2014
This is the code I'm trying to run:
%Blind embedding and linear correlation detection
clear all;
%Generate a reference pattern the same size as the images
wr=randn(112,92);
tm=mean2(wr);
wr=wr-tm;%zero mean
ts=std2(wr);
wr=wr/ts;%unit variance
%Show the reference pattern
figure
imshow(wr,[]);
%400 face images, 112 x 92 pixels, in 40 folders of 10 images each
numclass=40;
numface=10;
for s=1:numclass
for i=1:numface
%Add reference pattern to the image to embed a 1
wa=double(c0+wr);
%Add negative reference pattern to the image to embed a 0
nwr=wr*-1;
nwa=double(c0+nwr);
%Calculate linear correlation for images carrying a 1, a 0,
%or no watermark and store it into a vector
corr1(10*(s-1)+i)=sum(sum(wa.*wr))/(112*92);
corr0(10*(s-1)+i)=sum(sum(nwa.*wr))/(112*92);
corrN(10*(s-1)+i)=sum(sum(c0.*wr))/(112*92);
end
end
%Calculate the histograms for the detection-value vectors
[a1,b1]=hist(corr1,-3:0.1:3);
[a2,b2]=hist(corr0,-3:0.1:3);
[a3,b3]=hist(corrN,-3:0.1:3);
%Plot the histograms
figure
plot(b2,a2/400*100,'red');
gtext('m=0');
hold;
plot(b3,a3/400*100,'green');
gtext('No watermark');
plot(b1,a1/400*100,'blue');
gtext('m=1');
xlabel('Detection value');
ylabel('Percentage of images');
if true
% code
end
When I click 'Save and Run', it gives me this error:
??? Undefined function or method 'blind' for input arguments of type 'char'.
Can anyone help me out? Also the image I'm using is Lena.tiff. I know I need to change the directory from C: onwards but do I also need to change .bmp to .tiff? Any help would be much appreciated.

Alberto on 12 Apr 2014
Looks like you are using a function 'blind': there is not such command, and probably doesnt have a made up function.
The point is you are calling an undefined function.
Alberto on 12 Apr 2014
That's what the error message suggest.
I tried to run the code and doesn't appear any error message. Maybe the error is not the code.

Walter Roberson on 13 Apr 2014
Look at your first few characters:
%Blind
If for some reason the '%' is not being recognized as a comment character then that line would be interpreted as a call to "Blind" with the rest of the line as character arguments.
What, by the way, did you name your source file? The source file name must start with a letter, and be followed by letters, digits, or underscore (no spaces) to a maximum of 63 characters, after which there should be a '.m' extension.
Blake on 21 Apr 2014
Thank you very much I learnt a lot from that video and finally ran the code successfully