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## Main Question or Discussion Point

Hi there. I am solving an under-determined system of equations. The solver I've written seems to work fine, but I would like to have some control on the solution I obtain. From the infinite set of solutions of my system, I would like to use only those that fulfill some conditions. One of those conditions is that the elements of the solution should ##x_k\geq-1##. The other condition I would like it to meet is more difficult to explain, but basically it has to do with that there should be some relation between some sets of elements in the solution. Basically, the element ##x_1## should be equal to the element, let's say ##x_M##, and ##x_{M-c}## where c and M are constants and so on.

Is there a way to meet these conditions? I am programming this in fortran, and I am using lapack to solve the under-determined system (I'm using the dgels subroutine). The program finds a solution, but sometimes the conditions are not fulfilled, and the solutions I obtain are physically nonsensical.

Bye there.

Is there a way to meet these conditions? I am programming this in fortran, and I am using lapack to solve the under-determined system (I'm using the dgels subroutine). The program finds a solution, but sometimes the conditions are not fulfilled, and the solutions I obtain are physically nonsensical.

Bye there.

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