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Instant-use add-on functions for the Wolfram Language
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Replace repeated subexpressions in an expression with new symbols
ResourceFunction["SimplifyRepeatedSubexpressions"][expr] returns a list of the expr with repeated subexpressions removed, along with the replacement rules used to rewrite them in simpler form. |
"MinLeafCount" | 2 | minimum size of the subexpressions to be extracted |
"VariableNames" | Unique[]& | method to generate the names of the subexpressions |
Find the repeated term in the expression (a+b+c)3+(a+b+c)2:
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Reconstruct the original expression from the decomposed form:
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Finding many small common subexpressions may not be helpful:
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Find only the largest with "MinLeafCount":
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You can control the prefix used for subexpressions by providing a string:
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You can also control the names used for subexpressions by providing a list of variable names:
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Or by providing a generating function:
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The "VariableNames" option takes the subexpression as an argument:
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Remove the discriminant from the quadratic solution equations:
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Reconstruct the original expression from the decomposed form by applying ReplaceRepeated:
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The FullForm of subexpressions must match; in this case, no match is found:
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This is because the outermost Plus has four arguments and not just the a, b and c:
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If the input expression contains elements with HoldAll, HoldRest or HoldFirst, the contents will evaluate during the search:
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Simplify the third-degree polynomial solution:
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And the fourth-degree polynomial solution:
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Construct meaningful variable names based on their content:
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Wolfram Language 11.3 (March 2018) or above
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