changing value in a 2d array

hi, thank you for your help.

I would like to know how to change values in a 2d array. For example, I have an 2d array A as of 1000x1000, of all zero values

I want to change value in position, 1x1, 1x100, 1x1000 to value 1.

do you know a quick way of doing this?

Answer 1

[Rick Rosson]

Please try the following:

A(1,1) = 1;
A(1,100) = 1;
A(1,1000) = 1;

HTH.

[charlie]

please see my response below, many thanks

Answer 2

[Walter Roberson]

A(1,[1 100 1000]) = 1;

[charlie]

please see my response below, many thanks

Answer 3

[charlie]

thank you guys, when everytime i run the above function, Matlab automatically loop through the entire 1000x1000 array. as the following:

   0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0
     0     0     0     0     0

I dont have any for loop in there, and this took a lot of time to compelete the entire program, do you have any ideas?

[James Tursa]

Please post your code, or a simplified version of it that will show the problem you are having.

[Oleg Komarov]

It doesn't loop, but it outputs the result on the command window. Use ";" as included in the code snippets to supress screen print.

[bym]

agree with Oleg, just didn't post soon enough!

[charlie]

thank you very much, you guys are awsome