how i can see the results

Questions
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1

i have a problem
i can use sum function that it have sinous
but it is’nt run and just i&j are misplased without latest result!!
please help me
the example is:
Sum[(sin[[Pi][Cross]i[Divide]2]*sin[[Pi][Cross]j[Divide]2])[Cross](i^2+(j^2[Cross]0.3))[Divide](i^4+2[Cross]i^2[Cross]j^2+j^4),{i,1,9},{j,1,9}]

2

There were a couple of little problems. For example, Mathematica is case sensitive, i.e. Sin is different from sin. “Cross” is the vector cross product, and I suppose you mean the standard product. Also, when you post you might want to use code boxes. The following should work:

Sum[(Sin[Pi i/2]*Sin[Pi j/2]) (i^2 + (j^2 0.3))/(i^4 + 2 i^2 j^2 + j^4), {i, 1, 9}, {j, 1, 9}]

Cheers,

Marco

3

thank you very much