TRIDAG Procedure
Solves tridiagonal systems of linear equations.
Usage
TRIDAG, a, b, c, r, u
Input Parameters
a—An n-element vector containing n – 1 subdiagonal elements. Element a0 is ignored.
b—An n-element vector containing n diagonal elements.
c—An n-element vector containing n – 1 superdiagonal elements. Element cn–1 is ignored.
r—An n-element vector containing the right-hand side of the equation ATu = r.
Output Parameters
u—An n-element floating-point vector containing the solution for tridiagonal systems of linear equations.
Keywords
None.
Discussion
The input vectors a, b, c, and r are not modified by TRIDAG. They contain, respectively, the subdiagonal, diagonal, and superdiagonal elements of A, and the right-hand side of the equation:
ATu = r
The solution is stored in the variable u.
note | Because PV-WAVE subscripts are in column-row order, the above equation is written as ATu = r, rather than as Au = r. |
See Also
TRIDAG is based on a routine of the same name in Numerical Recipes in C: The Art of Scientific Computing, by Flannery, Press, Teukolsky, and Vetterling, Cambridge University Press, Cambridge, MA, 1988, and is used by permission.
