local changes, need to check the correctness
efficiency improved
intermediate version. Fixed an improper sign, the new version seems to work with variable coefficients
works with non-constant coefficient alpha, as well as non-uniform mesh
forms the 7-diagonal matrix instead of the matrix consisting of 4 3-diagonal blocks and solves the system of equations with the help of the internal octave solver for banded matrices. Works in the case alpha(x)=-x, and delta(x)=0
deleted unnessessary functions
added a new file with very brief description of what we're doing
the file that describes what we're doing
cleaned up the code a bit
Merge branch 'fast'
Code has been tested