The method Invert calculates the inverse of a quadratic matrix and stores the result on top of the original matrix (thereby destroying the original contents). The matrix inversion is carried out using the LUdecomposition procedure (decomposition into two triangle matrices). It must not be applied to nonquadratic matrices.
The function returns the value TRUE, if the inversion has been completed successfully. In case of a FALSE value, the resulting matrix is undefined. The following reasons can cause a failure of the method Invert :
 the matrix is not quadratic
 the routine runs out of heap memory
 the matrix is singular
Invert increments the global variable ProcStat and calls the feedback routine MathFeedBackProc in order to allow feedback to the user during time consuming calculations. The Invert function can be terminated by setting the global variable AbortMathProc to TRUE.
