compute triple summation for my homework

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androidguy 2016-9-19

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评论： Walter Roberson 2016-9-21

采纳的回答： Walter Roberson

hello guys

I have need to compute the following summation for my homework. Any hint or pseudo code would be helpful. Thanks.

Edit - "p" is a vector containing numbers and p(x) refers to the element position in that vector and "y" is a symbol

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androidguy 2016-9-19

编辑：Walter Roberson 2016-9-19

using wolfram i got something like this -

https://www.wolframalpha.com/input/?i=(sum(sum(p(x)+*+y(x,t)%5Em)+m+from+1+to+3,+x+from+0+to+2,+t+from+1+to+3))

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Walter Roberson 2016-9-19

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Since y is a symbol, you will need to use the Symbolic Toolbox.

You might be tempted to use symsum() for this, but symsum has the limitation that symbolic variables cannot be used for indexing of arrays.

So... ndgrid, calculate the formula for each point, and then sum() along the dimensions until you get a scalar result.

My teacher said that it is okay to start the second summation from 1 instead of 0. Also how do i assign variables for each varying index? For example when x=1 and t=1, i need a variable like y11 and when x=2 and t=2 y22 and so on. How can i do this?

Walter Roberson 2016-9-21

在 MATLAB Online 中打开

y = sym('y', [3, 2]);
y(t, x)

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