how to create matrices efficiently

Hi!

let's say I have 10 different angles. So I have a1, a2, a3, ... a10. I need to calculate 10 different 2x2 matrices depending those angles and save them. So my matrices will be [cos(a1), sin(a1); sin(a1), -cos(a1)] and so on. Question is how I can make those matrices without writing all 10 matrix by hand? I've tried make those by for loop and I think my problem is that I need multiple matrices instead vectors.

[Azzi Abdelmalek]

This is not clear

[Roger Stafford]

Just a note of caution. In case those 2x2 matrices were intended to be rotation matrices by the angles a1, a2, ..., the signs are wrong in the second column.

Answer 1

[per isakson]

Here is a start

    >> f = @(a) [cos(a), sin(a); sin(a), -cos(a)]; 
    >> f(pi)
    ans =
       -1.0000    0.0000
        0.0000    1.0000
    >>

where

    f = @(a) [cos(a), sin(a); sin(a), -cos(a)];

Search the help for "Anonymous Functions"

Answer 2

[Kasper]

That helped so much!! Thank You!