Maybe this is the fault of how the IDL User Forum works with line returns or tabs or blank spaces from some keyboards, but there is something wrong with how your variables and operations appear in your original message. Could you possibly repost, preferably using IDL array syntax. Thus, if A is a 2 x 3 matrix, then it should have an assignment statement that looks like this: A = [[1.0,0.0],[0.0,2.0],[4.0,0.0]] You have examples in your original message that look like either 2x2 matrices or 2x2x3 arrays. After this, if you list line by line, just one operation per line, what equations IDL should be solving, maybe with a ';' comment explanation at the end of each statement, then perhaps someone in the group can help find the solution. Like I suggested, there may be a problem for your keyboard to type directly into IDL's User Forum textbox. In this case, you might want to first write you message in a simple text editor (like Notepad) and then just paste it into the User Forum textbox. Best of luck, James Jones