LinearSolveFunction[...][b] finds the solution to the matrix equation m.xb for the specific vector or matrix b.
In standard output format, only the dimensions element of a LinearSolveFunction object is printed explicitly. The remaining elements are indicated by <>.
dimensions specifies the dimensions of the matrix m from which the LinearSolveFunction was constructed.
b for the specific vector or matrix b. 
EXAMPLES
Basic Examples 
Scope 