Non-graphing calculator supporting complex matrices?

[supernumero]

(04-27-2014 03:19 AM)Thomas Klemm Wrote:  

(04-26-2014 11:53 PM)supernumero Wrote:  in particular, finding complex eigenvectors of real matrices

How would you do that with the HP-15C?

Good question. I did not mean to say I had used the 15C for this purpose; I was merely referring to the fact that the 15C supported complex matrices, and it is necessary to deal with complex matrices to find complex eigenvectors (even of real matrices). (I'm assuming the eigenvalues have already been found by some method---think of a 3x3 matrix whose real eigenvalue can be SOLVEd for, leading to a quadratic for the remaining pair of possibly complex eigenvalues. There would still remain the problem of finding the complex eigenvectors.)

The 15C's support of complex matrices was limited, and *clumsy*. For the purpose of finding complex eigenvectors the most useful operation, that of taking a matrix to reduced echelon form (or, at the very least, the ability to perform row operations: subtract X times row A from row B so a user or a program could do this step-by-step) was, unfortunately, missing from the 15C. Surely one could write a program to carry out these row operations using the 15C's complex arithmetic, but the memory was so limited---perhaps someone patient enough could carry out this plan in one of the Swiss 15C clones with extended memory.

I am almost feeling up to the challenge to do this for the 34S. Extending (real) M+x to become (CPLX)M+x is key for the task you asked about, and is something the 15C missed...

SN