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POPARFOR with if/else clause based on external boolean
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  1. POPARFOR with if/else clause based on external boolean
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    copied!<p>I have written a simple chemical simulation which calculates the properties of a large number of grid-boxes in parallel. Accordingly, I index the Y-dimension using a parallel loop:</p> <pre><code>function[outputArray] = stackTest() numX = 10; numY = 10; numZ = 10; outputArray = zeros(numX,numY,numZ); for iX = 1:numX parfor iY = 1:numY coreArray = outputArray(iX,iY,:); for iZ = 1:numZ tempNum = iX*iY*iZ; coreArray(1,1,iZ) = tempNum; end outputArray(iX,iY,:) = coreArray; end end end </code></pre> <p>This works fine. However, I am using booleans to control whether or not certain actions are performed, as shown in the following code. This works fine when using a simple <code>for</code> loop on Y, but when using <code>parfor</code>, the code fails with a claim that <code>optionalArg</code> is not defined:</p> <pre><code>function[outputArray] = stackTest(controlArg) numX = 10; numY = 10; numZ = 10; outputArray = zeros(numX,numY,numZ); if (controlArg) optionalArg = 10; end for iX = 1:numX parfor iY = 1:numY coreArray = outputArray(iX,iY,:); for iZ = 1:numZ tempNum = iX*iY*iZ; if controlArg tempNum = tempNum * optionalArg; end coreArray(1,1,iZ) = tempNum; end outputArray(iX,iY,:) = coreArray; end end end </code></pre> <p><code>stackTest</code> now works fine if <code>controlArg = true</code>, but not if <code>controlArg = false</code>; the only way around it I have found is to define <code>optionalArg</code> independent of <code>controlArg</code>. Needless to say this is a simplified version of the problem, but I would be grateful to anyone that can explain this to me; I suspect it's a subset of the problems that <code>parfor</code> loops have with globals, but since I am defining no globals I'm a little confused.</p> <p>Regards,</p> <p>Skipsh</p>
 

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