MATLAB BUILDER JA 2 Guide de l'utilisateur télécharger pdf (Page 96)

4 Using MWArra y Classes

a.set(index, 2.0);

else if (index[1] == index[0]+1 || index[1] == index[0]-1)

a.set(index, -1.0);

}

The example allocates the 4-by-4 sparse matrix with a capacity of 10 nonzero

elements. Initially, the array has no nonzero elements. The

for loops set the

array’s values using an index array.

Sparse arrays allocate storage only for the nonzero eleme nts that are

assigned. This e xample preallocates the array with a capacity of 10 elements

because it is known in advance that this many nonzeros are needed. If you

set additiona l zero e lements to nonzero v alu es, the allocated ca pa city is

automatically increased to accommodate the new values.

Examples of Using get. The

get methods work like the set methods. The

get methods support indexing through one-based offset or index array. The

next example displays the elements of an N-dim ensio nal array where all

indices are equal:

public void printDiagonals(MWNumericArray a)

{

int[] dims = a.getDimensions();

int n = dims[0];

for (int i = 1; i < dims.length; i++)

{

if (dims[i] < n)

n = dims[i];

}

for (int i = 1; i <= n; i++)

{

for (int j = 0; j < dims.length; j++)

dims[j] = n;

System.out.print("[");

for (int j = 0; j < dims.length; j++)

System.out.print(i + (j!=dims.length-1?",":""));

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MATLAB BUILDER JA 2 Guide de l'utilisateur Page 96