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annotate toolbox/poisson.m @ 2:c124219d7bfa draft

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Re-add the 1995 toolbox after noticing the statement in the ~higham/mctoolbox/ webpage.
author Antonio Pino Robles <data.script93@gmail.com>
date Thu, 07 May 2015 18:36:24 +0200
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Antonio Pino Robles <data.script93@gmail.com>
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1 function A = poisson(n)
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2 %POISSON Block tridiagonal matrix from Poisson's equation (sparse).
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3 % POISSON(N) is the block tridiagonal matrix of order N^2
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4 % resulting from discretizing Poisson's equation with the
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5 % 5-point operator on an N-by-N mesh.
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7 % Reference:
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8 % G.H. Golub and C.F. Van Loan, Matrix Computations, second edition,
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9 % Johns Hopkins University Press, Baltimore, Maryland, 1989
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10 % (Section 4.5.4).
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12 S = tridiag(n,-1,2,-1);
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13 I = speye(n);
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14 A = kron(I,S) + kron(S,I);