Variable input for linear equations system.

[majet]

Hi, I recently started the whole Excel VBA programming experience and used this forum a lot in the past weeks. Now I am stuck with this problem:

I have a simple matrix multiplication [Sigma]=[E]*[Epsilon] for the stiffness of composite materials. Sigma and Epsilon are 6 terms vectors and the complex rigidity matrix E is a 6x6 coefficients matrix with all terms known (ABD matrix).

Here is the twist: For every position of both Epsilon and Sigma vectors (1 to 6), the user must input a value for ONE of the two vectors. For instance he can define terms 1,2 and 6 of the Sigma vector and 3,4 and 5 of the Epsilon vector. Then, my software must be able to compute the 6 remaining terms. For instance the user can define that the composite plate remains flat (3 last terms of the Epsilon vector equal 0) while being submitted to a plane stress state (3 firsts terms not nil for Sigma vector).

Is there any way to make this automatically so I do not have to manually solve and then input the 64 possibilities of equations.

Any help would be greatly appreciated.

Thx in advance.

 

[AlphaFrog]

Have you considered using Array Names and Matrix Functions ?

MMULT Function

 

[majet]

I do not understand how I could perform the multiplication MMULT with variables to solve them afterwards. As I explained in my description, if terms 3,4 and 5 of the Epsilon vector are known numerical values and terms 1, 2 and 6 are variables, doing MMULT of the epsilon vector with my E 6x6 matrix would not provide the linear equation system that can be solved with the 3 known terms of the Sigma vector. MMULT will only compute numerical values and not allow me to build an algebric equation system with 3 variables, right ?

 

[majet]

I solved my problem iteratively computing the missing elements of both epsilon and sigma vectors and the solution converges for all the inputs I have tried so far.

Thx for your efforts.