MATLAB: Using a logic mask for selective data operations

logicmaskMATLAB

Hi All. I'm trying to use a logic mask to select data in a numerical matrix, rather than simply looping through each cell, and perform some mathematical operation, and then the inverse maks to perform a different operation. For example…
data = [-2, -4, 1, 3, 4, -6; -0.5, 2.4, 5, 9.8, 3, -11.2; 4, 3, -2, -1.5, 7, 10; 3, 4, -2.4, -3.3, -8, 10];
logicmaskneg = data < 0;
logicmaskpos = data > 0;
dataneg = data(logicmaskneg);
datapos = data(logicmaskpos);
So logicmaskneg and logicmaskpos keep the same matrix structure as data. But dataneg and datapos collapses the data matrix into one column. How do I apply the logic masks such that I can keep dataneg and datapos in the matrix organisation as data so I can continue to perform further calculations preserving the original column and row organisation?
Maybe I'm going about this the wrong way. My aim is to perform one operation on only the negative numbers and a different calculation on the positive numbers while preserving the data layout.
Any help and advice is much appreciated.
Thanks.

Best Answer

The ‘logicmaskneg’ and ‘logicmaskpos’ matrices become numeric matrices when used in any calculation.
See if this does whatt you want: 
data = [-2, -4, 1, 3, 4, -6; -0.5, 2.4, 5, 9.8, 3, -11.2; 4, 3, -2, -1.5, 7, 10; 3, 4, -2.4, -3.3, -8, 10];
logicmaskneg = data < 0;
logicmaskpos = data > 0;
dataneg = data(logicmaskneg);
datapos = data(logicmaskpos);
producing: 
dataneg =
           -2           -4            0            0            0           -6
         -0.5            0            0            0            0        -11.2
            0            0           -2         -1.5            0            0
            0            0         -2.4         -3.3           -8            0
datapos =
            0            0            1            3            4            0
            0          2.4            5          9.8            3            0
            4            3            0            0            7           10
            3            4            0            0            0           10
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