Is it possible to assembly a global matrix from many individual local matrices? Such as is done in stiffness matrix of a structural system?
For example, if k.1 yields a 2x2 matrix with positions in regards to the global matrix 11,12,21,22. And k.2 yields a 2x2 matrix with position 22,23,32,33 again in regards to a global position. Can MathCAD assemble the matrix with correct positioning without building k.1 and k.2 as a 3x3 and then simply adding together k.1 and k.2? Its simple enough when the global is a 3x3 assemble from a 2x2, but is much more strenuous when assembling a 10x10 matrix from (5) 3x3 matrices.
Mathcad has lots of possibilities with matrices, most of which you have to build yourself.
Does this help?
Oh! Just see that I am way too late.
But here's my attempt, for whatever its worth. Its very similar to Luc's but I got the impression that you want to add the new matrix rather than replace the old values. That could be also very easily accomplished using Luc's approach. Basically both are the same but my routine automatically enlarges the destination matrix if its too small.