## Version 1.1.0

• Single
• Double

### MC57 Assemble a set of ﬁnite-element matrices

This subroutine assembles a set of element matrices, that is, it forms the summation

$A=\sum _{l}{A}^{\left[l\right]},$

where each element matrix ${A}^{\left[l\right]}$ has entries only in the principal submatrix corresponding to the variables in element $l$. Each ${A}^{\left[l\right]}$ must be held in packed form as a small full square matrix, together with a list of the variables associated with element $l$. The assembled matrix $A$ has a symmetric sparsity pattern but may be unsymmetric. An option exists for assembling only the sparsity pattern of $A$. If the variables are not indexed contiguously, absent rows and columns may optionally be removed.