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Results tagged with pattern-matching
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user 97982
Questions on expression testing and manipulation through pattern matching and constructing efficient patterns.
3
votes
2
answers
45
views
Trouble with replacement rules for squared variables [duplicate]
I want to do replacement of products (because I am dealing with abstract projectors), but Mathematica seems to fail understanding this toy example replacement :
x y y /. {x y -> 1}
x y^2
because it …
- 375
5
votes
2
answers
189
views
Pattern recognition for products of variables
Pattern recognition doesn't work as I would expect when trying to match products, for example
Cases[a[1] b[1] a[2] b[2], x___ a[k_] b[k_] -> k, All]
{1}
Cases[a[1] b[1] a[2] b[2], a[k_] b[k_] -> k, …
- 375
4
votes
5
answers
247
views
How to make expression-dependent replacements?
Consider as a toy example that I want a replacement
which acts on
{x,1,2,3}
by replacing $x$ with the length of the list itself. In this example this should output
{4,1,2,3}
So I want a code that l …
- 375
5
votes
3
answers
384
views
Reversing the order of function arguments by a replacement rule
I am facing an issue when I try to reverse the arguments of a function in a replacement rule.
Let me give an example :
g[x3, x2, x1] /. {g[arg___] -> g[Sequence @@ Reverse[{arg}]]}
This outputs
g[x3 …
- 375
3
votes
1
answer
72
views
Troubles with BlankNullSequence in the case of multiplication
I have some trouble to use the triple underscore notation to use definitions with or without a term. Consider the following toy example
f[a___ x]:=1
{f[x],f[2x]}
This returns
{f[x],1}
whereas I wou …
- 375