Compare two matrices in Matlab

• matrix1=[1:20]';
• matrix2=[21:40]';
• combined_matrix1_and_matrix2=[matrix1 matrix2];

If the value is equal to a number of matrix1, then show the number of matrix2. When the number isn´t shown in matrix1, then the programm give the answer ´error´

I don't know how to build this programm

• for example:
• the value is 13
• matrix1 has this number.
• the programm have to show the value: 33.

See my myfile: http://www.mathworks.com/matlabcentral/fileexchange/47585-compare-m

Answer 1

[Iain]

 answer =  matrix2(matrix1 == number_of_interest)