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Science Forum Index » Math - Symbolic Forum » summing polynomials
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| Peter Schreiber |
 Posted: Sun Apr 27, 2008 6:11 pm |
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Guest
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Hi,
I would like to calculate following sum:
\!\(\*
StyleBox[\(∑\+\(i = 1\)\%4\(∑\+\(j = 1\)\%4\(∑\+\(k = 1\)\%4\(∑\+\(l = 1\)\%4 \ Hx^i*Hy^j*ρx^k*ρy^l\)\)\)\),
FontSize->18]\)
I got this working, but now I would like to accomplish 2 more things.
1. I would like to constrain the indices that
i+j+k+l=4 is valid. How can I do this?
2. I would like to add a multiplier in the sum called
\!\(W\_ijkl\), where i,j,k and l should have the
particular indices for each term.
I would appreciate any help with this.
Best Regards,
Peter |
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| sashap |
| Posted: Mon Apr 28, 2008 12:57 am |
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Guest
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On Apr 27, 11:11 pm, Peter Schreiber <schreiber.pete...@gmail.com>
wrote:
Quote: Hi,
I would like to calculate following sum:
\!\(\*
StyleBox[\($B-t(B\+\(i = 1\)\%4\($B-t(B\+\(j = 1\)\%4\($B-t(B\+\(k = 1\)\%4\($B-t(B\+\(l = 1\)\%4 \ Hx^i*Hy^j*$B&Q(Bx^k*$B&Q(By^l\)\)\)\),
FontSize->18]\)
it would not hurt to convert your input into InputForm, so that
it is readable, and reads as
Sum[H x^i*H y^j*\[Rho] x^k*\[Rho] y^l, {i, 1, 4}, {j, 1, 4}, {k, 1,
4}, {l, 1, 4}]
and people know it is in Mathematica language.
Quote:
I got this working, but now I would like to accomplish 2 more things.
1. I would like to constrain the indices that
i+j+k+l=4 is valid. How can I do this?
2. I would like to add a multiplier in the sum called
\!\(W\_ijkl\), where i,j,k and l should have the
particular indices for each term.
I would appreciate any help with this.
I think the following meets the requirements:
Sum[KroneckerDelta[i + j + k + l - 7]*Subscript[W, i, j, k, l]*x^i*
y^j*x^k*y^l, {i, 1, 4}, {j, 1, 4}, {k, 1, 4}, {l, 1, 4}]
where you could change 7 to be other number you would
like the sum of polynomial exponents to be equal to.
Oleksandr Pavlyk
Quote:
Best Regards,
Peter |
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