-
-
Save cbellei/8ab3ab8551b8dfc8b081c518ccd9ada9 to your computer and use it in GitHub Desktop.
Tridiagonal Matrix Algorithm solver in Python
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
import numpy as np | |
## 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 | |
and to http://www.cfd-online.com/Wiki/Tridiagonal_matrix_algorithm_-_TDMA_(Thomas_algorithm) | |
''' | |
nf = len(d) # number of equations | |
ac, bc, cc, dc = map(np.array, (a, b, c, d)) # copy arrays | |
for it in xrange(1, nf): | |
mc = ac[it-1]/bc[it-1] | |
bc[it] = bc[it] - mc*cc[it-1] | |
dc[it] = dc[it] - mc*dc[it-1] | |
xc = bc | |
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] | |
return xc |
How to be in case when on diagonal line during computing we get zero?
for example:
A = np.array([[6,2,0,0],[3,1,4,0],[0,1,7,5],[0,0,3,4]],dtype=float)
How to be in case when on diagonal line during computing we get zero?
for example:
A = np.array([[6,2,0,0],[3,1,4,0],[0,1,7,5],[0,0,3,4]],dtype=float)
@BatoNam, there is condition, when you could use this method. Conditional is
abs(a[i]) + abs(c[i]) <= abs(b[i]) for each i
xc is just a reference to bc
It's pointless.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Thanks! That helps.