Sum of a function
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Hello everyone, I am stucked on how to write particular code for a Nash-Cournout oligopolistic equilibrium problem. I have written everything correctly and it ran successfully. The only situation I am in presently is trying to vary a particular step. To be more precise
I need code for the following:
is random for every 
is random for every and
is random for every . I need to execute the following Quad program $c_j(x_j) = \frac{1}{2}x{_j}^{'} P_j x_j+ {q_j}^{'} x{_j}$. I will be glad if I can get a prompt help on this.https://www.mathworks.com/matlabcentral/answers/uploaded_files/226241/Screenshot_20190625-093751.png
Thanks
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Himanshu Rai
2019-6-25
编辑：Himanshu Rai
2019-6-25
The expression below should solve your problem. Also write questions properly - 
would be scalar, so c is a vector. P and x are normal matrices, and q is a vector. This should solve your problem.
would be scalar, so c is a vector. P and x are normal matrices, and q is a vector. This should solve your problem.PS - Also update your question, and attach the image file there
c = x' * P * x / 2 + q' * x
8 个评论
Olawale Kazeem
2019-6-25
Himanshu Rai
2019-6-25
编辑：Himanshu Rai
2019-6-25
From what is specified in the question 
appears to be a scalar value. The same goes for 
and 
appears to be a scalar value. The same goes for and
Olawale Kazeem
2019-6-25
Himanshu Rai
2019-6-25
From your comment 
, 
and 
, are the dimensions of your matrices. But this doesn't satisfy usual matix operation rules for the evaluation of you expression. Please specify more clearly, what (dimension of the) vector you are referring to, and by size of matrix to be 3 do you mean it is a square matrix ?
, and , are the dimensions of your matrices. But this doesn't satisfy usual matix operation rules for the evaluation of you expression. Please specify more clearly, what (dimension of the) vector you are referring to, and by size of matrix to be 3 do you mean it is a square matrix ?
Olawale Kazeem
2019-6-25
Himanshu Rai
2019-6-25
编辑：Himanshu Rai
2019-6-25
All right, so now I got what your question is, but still your dimensions doesn't satisfy rules of matrix opeations.
is 
, 
is 
, so 
will be .
is 
, is , so 
will be .But we can't add these two results.
Olawale Kazeem
2019-6-25
Himanshu Rai
2019-6-25
Well if 
is 
, then 
can't be calculated, because again the matrices are incompatible
is , then can't be calculated, because again the matrices are incompatible更多回答（1 个）
Olawale Kazeem
2019-6-25
0 个投票
10 个评论
Himanshu Rai
2019-6-25
I have updated my answer based on the image file you provided. Update your question, attach this file in the question and also don't comment as answer
Olawale Kazeem
2019-6-25
Thanks, but I still don't understand how to treat the js, should I write each differently? I mean getting $c_1(x_1)$, $c_2(x_2)$, ⋯ .
separately. I need a code that can run everything together once.
separately. I need a code that can run everything together once.
Olawale Kazeem
2019-6-25
How do I get a function 
going by what you suggested up there?
going by what you suggested up there?
Himanshu Rai
2019-6-25
Use
sum(c) % here c is what you get from the expression in the answer
Olawale Kazeem
2019-6-25
I get that, I hope this is my final question. What if my N is greater than the dimension of the matrices? It is clear now that the 
s are the entries of the vector x. If the vector is of dimension 10, but I need to sum up to $N=20$, how possible is this?
s are the entries of the vector x. If the vector is of dimension 10, but I need to sum up to $N=20$, how possible is this?
Himanshu Rai
2019-6-25
This doesn't make any sense - how can we add 20 elements, if there are only 10 elements in vector.
Olawale Kazeem
2019-6-25
Himanshu Rai
2019-6-25
is a scalar, whereas c is a vector.
Olawale Kazeem
2019-6-25
I suppose my definition of x is wrong. I defined 
; 
; and 
; . $c = 0.5*x'*P*x+q'*x$. This gives a 
matrix.
; ; and ; . $c = 0.5*x'*P*x+q'*x$. This gives a matrix.
Himanshu Rai
2019-6-25
This is not x, but 
. 
is a vector but x is a matrix. And what you denote by c above is actually 
. is a vector but x is a matrix. And what you denote by c above is actually 类别
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