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4 Using MWArra y Classes

00-12]

Calling newSparse. The call to newSparse passes three arrays: an array of

matrix data (

x), an array containing the row indices of x (rowindex), and an

array of column indices of

x (colindex). The number of rows (4) and columns

(4) are also passed, as well as the type (

MWClassID.DOUBLE):

double[] x = { 2.0, -1.0, -1.0, 2.0, -1.0,

-1.0, 2.0, -1.0, -1.0, 2.0 };

int[] rowindex = {1, 2, 1, 2, 3, 2, 3, 4, 3, 4};

int[] colindex = {1, 1, 2, 2, 2, 3, 3, 3, 4, 4};

MWNumericArray a =

MWNumericArray.newSparse(rowindex, colindex, x, 4, 4,

MWClassID.DOUBLE);

Constructing the Arra y Without Setting Rows and Columns. You could

have passed just the row and column arrays and let the

newSparse method

determine the number of rows and columns from the maximum values of

rowindex and colindex as follows:

MWNumericArray a = MWNumericArray.newSparse(rowindex, colindex,

x, MWClassID.DOUBLE);

Constructing the Array from a Full M a trix. You can also construct a

sparse array from a full matrix using

newSparse.Thenextexamplerewrites

the previous example using a full matrix:

double[][] x = {{ 2.0, -1.0, 0.0, 0.0},

{-1.0, 2.0, -1.0, 0.0},

{ 0.0 -1.0, 2.0, -1.0},

{ 0.0, 0.0, -1.0, 2.0 }};

MWNumericArray a = MWNumericArray.newSparse(x,

MWClassID.DOUBLE);

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MATLAB BUILDER JA 2 Guia do Utilizador Página 92