How to use if statement inside a for loop?

I'm currently trying to print out something if the difference between the plots is bigger than 100.

for i = 2:10

plot(x(:,25+i)

dif(:,i) = x(:,25+i) - x(:,25+(i-1)); %error here

if dif >200

fprintf( ) %print out the x value where it was triggered

else

fprintf('nothing')

end

I'm having trouble saving each occurance that it happens.

Answer 1

[Walter Roberson]

for i = 2:10
  plot(x(:,25+i)) ; hold on 
  dif(:,i) = x(: ,25+i) - x(:,25+(i-1));
  mask = dif(:, i) > 200
  if any(mask) 
      fprintf('col %d: %s\n', 25+i, mat2str(x(mask, 25+i))); %print out the x value where it was triggered
    else
       fprintf('col %d: nothing\n');
     end
end

[Emily]

Thanks for the response, unfortunately I'm still getting an error here,

dif(:,i) = x(: ,25+i) - x(:,25+(i-1));

[Walter Roberson]

you have not told us what the error message is, or what size of x is, or whether dif exists before this point in the code.

[Emily]

Size of x is about 2000x2000 value from a struct, and there is a difference between the some of the figures but depends on the input file number.

I was able get it working by getting rid of the (:,i) and only using dif=. But now not sure how to display the X-axis value on where this is happening as the code prints out the Y-axis value of the looped graphs when mask is detected.

[Walter Roberson]

The code I showed cannot print out the y axis values. The code I showed uses mat2str(x(mask, 25+i)) which displays x values, not y values.

The vectorized form of the code would look more like

i = 2:10;
plot(x(25+i))
dif = x(:,25+i) - x(:,25+i-1);
mask = dif > 200;
for c = 1:size(dif,2)
    submask = mask(:,c);
    if any(submask)
      fprintf('col %d: %s\n', 25+c+1, mat2str(x(submask, 25+c+1))); %print out the x value where it was triggered
    else
       fprintf('col %d: nothing\n', 25+c+1);
    end
end