sympy match has difficulty with modulo
Following this StackOverflow question, and a fix provided by @smichr, I tried the following:
>>> from sympy import *
>>> k,m,n = symbols("k m n", integer=True)
>>> (3*k+4)%2 - k%2
0 # it works with the fix above. Thank you!
>>> p = Wild('p')
>>> q = Wild('q')
>>> e = (2*k+7)%5 + 7*k+7
>>> e
7*k + Mod(2*k + 2, 5) + 7
>>> e.match(p%5+p)
>>> e.match((p+5*q)%5+p)
>>> e.match(p%5+p+5*q)
q_: k + 1, p_: 2*k + 2
I expected the first or second e.match to work for me (p:7*k+7 for first one and p:7*k+7,q:-k for second one), but it didn't. Is this a bug? If yes, is there a fix/workaround?
python match sympy modulo
asked Nov 14 '18 at 17:04
Salem DerisaviSalem Derisavi
978
add a comment |
Following this StackOverflow question, and a fix provided by @smichr, I tried the following:
>>> from sympy import *
>>> k,m,n = symbols("k m n", integer=True)
>>> (3*k+4)%2 - k%2
0 # it works with the fix above. Thank you!
>>> p = Wild('p')
>>> q = Wild('q')
>>> e = (2*k+7)%5 + 7*k+7
>>> e
7*k + Mod(2*k + 2, 5) + 7
>>> e.match(p%5+p)
>>> e.match((p+5*q)%5+p)
>>> e.match(p%5+p+5*q)
q_: k + 1, p_: 2*k + 2
I expected the first or second e.match to work for me (p:7*k+7 for first one and p:7*k+7,q:-k for second one), but it didn't. Is this a bug? If yes, is there a fix/workaround?
python match sympy modulo
asked Nov 14 '18 at 17:04
Salem DerisaviSalem Derisavi
978
add a comment |
Following this StackOverflow question, and a fix provided by @smichr, I tried the following:
>>> from sympy import *
>>> k,m,n = symbols("k m n", integer=True)
>>> (3*k+4)%2 - k%2
0 # it works with the fix above. Thank you!
>>> p = Wild('p')
>>> q = Wild('q')
>>> e = (2*k+7)%5 + 7*k+7
>>> e
7*k + Mod(2*k + 2, 5) + 7
>>> e.match(p%5+p)
>>> e.match((p+5*q)%5+p)
>>> e.match(p%5+p+5*q)
q_: k + 1, p_: 2*k + 2
I expected the first or second e.match to work for me (p:7*k+7 for first one and p:7*k+7,q:-k for second one), but it didn't. Is this a bug? If yes, is there a fix/workaround?
python match sympy modulo
asked Nov 14 '18 at 17:04
Salem DerisaviSalem Derisavi
978
Following this StackOverflow question, and a fix provided by @smichr, I tried the following:
>>> from sympy import *
>>> k,m,n = symbols("k m n", integer=True)
>>> (3*k+4)%2 - k%2
0 # it works with the fix above. Thank you!
>>> p = Wild('p')
>>> q = Wild('q')
>>> e = (2*k+7)%5 + 7*k+7
>>> e
7*k + Mod(2*k + 2, 5) + 7
>>> e.match(p%5+p)
>>> e.match((p+5*q)%5+p)
>>> e.match(p%5+p+5*q)
q_: k + 1, p_: 2*k + 2
I expected the first or second e.match to work for me (p:7*k+7 for first one and p:7*k+7,q:-k for second one), but it didn't. Is this a bug? If yes, is there a fix/workaround?
python match sympy modulo
python match sympy modulo
asked Nov 14 '18 at 17:04
Salem DerisaviSalem Derisavi
978
asked Nov 14 '18 at 17:04
Salem DerisaviSalem Derisavi
978
edited Nov 14 '18 at 18:15
Salem Derisavi
asked Nov 14 '18 at 17:04
Salem DerisaviSalem Derisavi
978
asked Nov 14 '18 at 17:04
Salem DerisaviSalem Derisavi
978
asked Nov 14 '18 at 17:04
Salem DerisaviSalem Derisavi
978
978
add a comment |
add a comment |
1 Answer
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(Copying the same thing I wrote on the SymPy issue)
match has very limited mathematical knowledge. It doesn't know that the 2*k in the Mod can be replaced with 7*k.
I'm not sure if this would be easy to fix. match is already pretty complicated with the limited mathematical matching it does. A better design would likely be needed to solve problems like this. Actually this strikes me as the sort of problem that you would need an SMT solver to solve, but maybe there are simpler algorithms that could do it.
Sorry this doesn't give a direct answer on how to solve the problem.
answered Nov 15 '18 at 22:10
asmeurerasmeurer
58.2k16113186
add a comment |
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(Copying the same thing I wrote on the SymPy issue)
match has very limited mathematical knowledge. It doesn't know that the 2*k in the Mod can be replaced with 7*k.
I'm not sure if this would be easy to fix. match is already pretty complicated with the limited mathematical matching it does. A better design would likely be needed to solve problems like this. Actually this strikes me as the sort of problem that you would need an SMT solver to solve, but maybe there are simpler algorithms that could do it.
Sorry this doesn't give a direct answer on how to solve the problem.
answered Nov 15 '18 at 22:10
asmeurerasmeurer
58.2k16113186
add a comment |
(Copying the same thing I wrote on the SymPy issue)
match has very limited mathematical knowledge. It doesn't know that the 2*k in the Mod can be replaced with 7*k.
I'm not sure if this would be easy to fix. match is already pretty complicated with the limited mathematical matching it does. A better design would likely be needed to solve problems like this. Actually this strikes me as the sort of problem that you would need an SMT solver to solve, but maybe there are simpler algorithms that could do it.
Sorry this doesn't give a direct answer on how to solve the problem.
answered Nov 15 '18 at 22:10
asmeurerasmeurer
58.2k16113186
add a comment |
(Copying the same thing I wrote on the SymPy issue)
match has very limited mathematical knowledge. It doesn't know that the 2*k in the Mod can be replaced with 7*k.
I'm not sure if this would be easy to fix. match is already pretty complicated with the limited mathematical matching it does. A better design would likely be needed to solve problems like this. Actually this strikes me as the sort of problem that you would need an SMT solver to solve, but maybe there are simpler algorithms that could do it.
Sorry this doesn't give a direct answer on how to solve the problem.
answered Nov 15 '18 at 22:10
asmeurerasmeurer
58.2k16113186
(Copying the same thing I wrote on the SymPy issue)
match has very limited mathematical knowledge. It doesn't know that the 2*k in the Mod can be replaced with 7*k.
I'm not sure if this would be easy to fix. match is already pretty complicated with the limited mathematical matching it does. A better design would likely be needed to solve problems like this. Actually this strikes me as the sort of problem that you would need an SMT solver to solve, but maybe there are simpler algorithms that could do it.
Sorry this doesn't give a direct answer on how to solve the problem.
answered Nov 15 '18 at 22:10
asmeurerasmeurer
58.2k16113186
answered Nov 15 '18 at 22:10
asmeurerasmeurer
58.2k16113186
answered Nov 15 '18 at 22:10
asmeurerasmeurer
58.2k16113186
answered Nov 15 '18 at 22:10
asmeurerasmeurer
58.2k16113186
58.2k16113186
add a comment |
add a comment |
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