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I am working on a matrix algebra-based project for an unrelated class, but unfortunately, I have no background in matrix algebra. I have managed so far to do most of the work, but I am stuck in my search for the right BLAS or LAPACK subroutine which could solve the following problem:

y = A*x

where y and x are KNOWN vectors, and A is an UNKNOWN matrix. I have found the subroutine dgemv which solves y = A*x, but with A as a KNOWN matrix and y as a KNOWN vector.

As additional information, A is a 4x4 matrix, y, and x are known 4-d vectors. In matrix A, the bottom row is just 0,0,0,1, and the first three elements of column 4 are the same as the elements of vector y.

So it looks like this:

[knownY] [unknown unknown unknown knownY] [0.0]

[knownY] = [unknown unknown unknown knownY]*[0.0]

[knownY] [unknown unknown unknown knownY] [0.0]

[ 1.0 ] [ 0.0 0.0 0.0 1.0 ] [1.0]

My attempt has been to look through lapack and blas for a subroutine, but I cannot find one where the two vectors are known and the matrix is what I am trying to solve for.

Thanks!

-miss fangula

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# Homework Help: Lapack/blas routine to solve y = Ax

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