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How to evaluate parts of an expression, but not other parts?


Dear all,

I'd like to use the TreePlot function to visualise the expression of a
dynamic programming problem I am working on.

If I have something like: ( (a+b) + (c+d )

Mathematica helpfully simplifies this to: a + b + c + d

But I'd prefer it to be in the original form.

I can't write Hold[ ( (a+b) + (c+d) )] because I do want a,b,c & d to
be evaluated.

I want to write something like:
Hold[ ( (Evaluate[a]+Evaluate[b]) + (Evaluate[c]+Evaluate[d]) ) ]

But this just leaves the Evaluate expressions unevaluated.

Any help greatly appreciated.

Thanks,
Julian.



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