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POMatlab function handle workspace shenanigans
 

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  1. POMatlab function handle workspace shenanigans
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    <p><strong>In short</strong>: is there an elegant way to restrict the scope of anonymous functions, or is Matlab broken in this example?</p> <p>I have a function that creates a function handle to be used in a pipe network solver. It takes as input a Network state which includes information about the pipes and their connections (or edges and vertices if you must), constructs a large string which will return a large matrix when in function form and "evals" that string to create the handle.</p> <pre><code>function [Jv,...] = getPipeEquations(Network) ... %// some stuff happens here Jv_str = ['[listConnected(~endNodes,:)',... ' .* areaPipes(~endNodes,:);\n',... anotherLongString,']']; Jv_str = sprintf(Jv_str); %// This makes debugging the string easier eval(['Jv = @(v,f,rho)', Jv_str, ';']); </code></pre> <p>This function works as intended, but whenever I need to save later data structures that contain this function handle, it requires a <strong>ridiculous</strong> amount of memory (150MB) - coincidentally about as much as the entire Matlab workspace at the time of this function's creation (~150MB). The variables that this function handle requires from the getPipeEquations workspace are not particularly large, but what's even crazier is that when I examine the function handle:</p> <pre><code>&gt;&gt; f = functions(Network.jacobianFun) f = function: [1x8323 char] type: 'anonymous' file: '...\pkg\+adv\+pipe\getPipeEquations.m' workspace: {2x1 cell} </code></pre> <p>...the workspace field contains everything that getPipeEquations had (which, incidentally is <em>not</em> the entire Matlab workspace).</p> <p>If I instead move the eval statement to a sub-function in an attempt to force the scope, the handle will save much more compactly (~1MB):</p> <pre><code>function Jv = getJacobianHandle(Jv_str,listConnected,areaPipes,endNodes,D,L,g,dz) eval(['Jv = @(v,f,rho)', Jv_str, ';']); </code></pre> <p>Is this expected behavior? Is there a more elegant way to restrict the scope of this anonymous function?</p> <p><em>As an addendum, when I run the simulation that includes this function several times, clearing workspaces becomes painfully slow, which may or may not be related to Matlab's handling of the function and its workspace.</em></p>
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    1. USNathan Donnellan
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    1. COHave you tried `evalin('base', ...)`? Does that make a difference?
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      1. USJohn Colby
    2. COI have not, but the workspace should already be limited to the scope of getPipeEquations.
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