Tridiagonal Matrix Algorithm solver in Python, using Numpy array - http://ofan666.blogspot.com/2012/02/tridiagonal-matrix-algorithm-solver-in.html

TDMAsolver.py

try:
   import numpypy as np    # for compatibility with numpy in pypy
except:
   import numpy as np      # if using numpy in cpython

## Tri Diagonal Matrix Algorithm(a.k.a Thomas algorithm) solver
def TDMAsolver(a, b, c, d):
    '''
    TDMA solver, a b c d can be NumPy array type or Python list type.
    refer to http://en.wikipedia.org/wiki/Tridiagonal_matrix_algorithm
    '''
    nf = len(a)     # number of equations
    ac, bc, cc, dc = map(np.array, (a, b, c, d))     # copy the array
    for it in xrange(1, nf):
        mc = ac[it]/bc[it-1]
        bc[it] = bc[it] - mc*cc[it-1] 
        dc[it] = dc[it] - mc*dc[it-1]

    xc = ac
    xc[-1] = dc[-1]/bc[-1]

    for il in xrange(nf-2, -1, -1):
        xc[il] = (dc[il]-cc[il]*xc[il+1])/bc[il]

    del bc, cc, dc  # delete variables from memory

    return xc

Could you add a license file to this code?

I agree. I appreciate the code snippet, but I would be happier if there was an explicit license. (I'm using this short code too.) Fortunately, it's one of the easiest methods in linear algebra, so it is easy to rewrite.