The subroutines LIBEM2, LIBEM3, LIBEMA, LEBEM3 and LEBEMA contain the parameter LSOL. This parameter is set .TRUE in all the test problems in this book, determining that a solution to a particular boundaryvalue problem is required in all cases.
Setting LSOL=.FALSE. allows a more sophisticated use of the subroutines. In this case the subroutines do not return a particular solution. The important results from the subroutine are contained in the parameters WKSPC1, WKSPC2, WKSPC3 and WKSPC4.
In chapters 45 the boundary functions are always found by solving a linear system of equations of the form

The data in these arrays enables more flexible use of the
boundary element method.
Some examples of more advanced use of the
routines are given here.
(i) Sometimes a range of different boundary conditions is required
to be applied on a boundary at one frequency. In this case
it is advisable to set up the matrices A and B once only and solve
the resulting linear systems in turn.
(ii) The boundary element method may only model part of a greater
coupled physical system. The matrices arising the BEM
form only submatrices of the complete model of the system.
The WKSPC1, WKSPC2 can be used as part
of the matrix that models the complete system.
The LSEM3 and LSEMA subroutines
These routines are structured similarly to the above. However, take note of the special structure of the matrices in chapter 6, before using them in the way described above.