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spilu_iludplot

Plots the sensitivity of ILUD for A.

Calling Sequence

spilu_iludplot(A)
data = spilu_iludplot(A)
data = spilu_iludplot(A,N)
[data,hAlpha] = spilu_iludplot(...)
[data,hAlpha,hDrop] = spilu_iludplot(...)

Parameters

A:

a n-by-n sparse matrix

N:

a 1-by-1 matrix of doubles, integer value, the number of points in the plot (default N = 100)

data:

a N-by-6 matrix of doubles, the values of the parameters

hAlpha:

a graphics handle, the alpha plot

hDrop:

a graphics handle, the drop plot

Description

For one particular matrix, plot norm(A-L*U)/norm(A) and nnz(L)+nnz(U), depending on alpha and drop for the ILUD method.

The columns of the array data are:

If the decomposition does not work for one value of the parameter, then norm(A-L*U)/norm(A) and nnz(L)+nnz(U) are set to Infinity.

Examples

A = [
34.    4.   -10.    0.  -3.
4.     24.  -8.     0.    0.
-10.  -8.     36.    0.    0.
0.     0.     0.     1.    0.
-3.     0.     0.     0.    6.
];
A = sparse(A);
spilu_iludplot(A);

// See on a 225-by-225 sparse matrix
path = spilu_getpath (  );
filename = fullfile(path,"tests","matrices","pde225.mtx");
A=mmread(filename);
[data,hLfil,hDrop] = spilu_iludplot(A);

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