Format Issues - will not accept a character or a double

Hi,

I'm having another really basic problem.

I want to use a different source for each plant, but it really doesn't like the format.

I get an error message at Xsource saying undefined function X_src_ for function of double or character if I change it. Am I missing something quite obvious?

Any help/advise is very much appreciated!

for plant = 1:5
   Xsource = x_src_(num2str(plant));     
   Ysource = y_src_(num2str(plant)) ;   
   X_shft = X_rot - x_src_(Xsource);
   Y_shft = Y_rot - y_src_(Ysource);
   [i] = find(X_shft > 0);

Answer 1

[Thorsten]

It would be helpful to know 1) what you want to achieve in your code and 2) how are the variables defined, like x_src_c, X_rot, Y_rot etc.

In particular, what is x_src_? You can check using

whos x_src_

Regardless of what x_src_ actually is, it you try to index into x_src_ using a string, e.g., '1' by using num2str(plant)). That seems strange to me. What do you want to achieve in this line of code?

[Chameleon17]

Hi, thanks for the answer. I've abandoned the string bit now, it doesn't make sense. I thought it might have been the problem with the double issue I suppose.

I'm just trying to use different locations for each of my plants.

for plants = 1:5

x_src_1 = 0; y_src_1 = 0; x_src_2 = 10000; y_src_2 = 10000; x_src_3 = -10000; y_src_3 = -10000; x_src_4 = 20000; y_src_4 = 20000; x_src_5 = -20000; x_src_5 = -20000;

Xsource = x_src_(plants); Ysource = y_src_(plants);

[Thorsten]

Do you mean like this?

for plants = -20000:10000:20000
 Xsource = plants; Ysource = plants;
 % further code here
end

or if you insists on the order of the plants

for plants = [0 10000 -10000 20000 -20000]
   Xsource = plants; Ysource = plants;
  % further code here
end

Answer 2

[Guillaume]

From your comment it looks like you're trying to index different variable names depending on a condition. The answer to that is very simple: DO NOT DO THAT. In matlab or any other language.

Create an array and index into this array

 X_src = [0, 10000, -10000, 20000, -20000];
 Y_src = [0, 10000, -10000, 20000, -20000];
 for plant = 1:5
    Xsource = X_src(plant);
    Ysource = Y_src(plant);
    %...
  end

Using numbered variables is very poor practice. There are many posts on this forum and a lengthy explanation in the faq detailing why.