Help with Coding problem
显示 更早的评论
I am trying to code the following in matlab.
<<
Following is my matlab code. But this doesn't give me the right result. Can somebody point out what am I doing wrong?
function [J] = funtc(x_t,c_mn,theta,M,N )
L = length(x_t );
l = 0:L-1;
m = 0:M-1;
n = 0:N-1;
J = 0 ;
for t = 1:L
xs = 0 ;
xp = 0 ;
for j = 1: length(n)
for k = 1: length(m)
xs = xs + c_mn(k,j)*exp(-pi*(l(t)-n(j))^2/theta^2)*exp(1i*2*pi*m(k)*(l(t)- n(j))/M);
xp = xp + c_mn(k,j)*exp(-pi*(l(t)-n(j))^2/theta^2)*exp(1i*2*pi*m(k)*(l(t)- n(j))/M)*(l(t)-n(j))^2/theta^3;
end
end
J = J + ((x_t (t) -xs) * conj (xp));
end
J = real(-4*J);
end
7 个评论
Geoff Hayes
2018-7-5
christina - in your code you consider
c_mn(m,n)
but aren't m and n arrays? Is this intentional? Or do you want to consider
c_mn(m(k),n(j))
instead?
Geoff Hayes
2018-7-5
Does that lead to a better (correct) solution?
christina
2018-7-6
Geoff Hayes
2018-7-6
I would try removing your arrays for n and m as I don't think they make the code easier to follow. Then your two inner loops would become simply
for n=0:N-1
for m=0:M-1
% etc.
end
end
Your first sum would (I think) be more like
for t = 0:L-1
xs = 0 ;
xp = 0 ;
for n = 0:N-1
for m = 0:M-1
xs = xs + c_mn(m+1,n+1) * exp(-(t - n)/theta) * exp(1i * 2 * pi * m * (t - n) / M);
xp = xp + c_mn(m+1,n+1) * exp(-(t - n)/theta) * exp(1i * 2 * pi * m * (t - n) / M) * (((t - n)^2) / theta^3);
end
end
% J = J + ...;
end
I'm assuming your theta input is the sigma in the equation. The above looks a little different than what you have so I'm not sure if it is better or worse.
I don't understand where the (1/sqrt(theta)) or a comes from (in your code). Or why a conjugate is used in the update to J...
christina
2018-7-9
Geoff Hayes
2018-7-9
But why just use conj on the one sum and not both?
回答（1 个）
Abraham Boayue
2018-7-10
编辑：Abraham Boayue
2018-7-10
Try this
function [J] = funtc(x_t,c,theta,M,N,L)
J = zeros(1,L);
for t = 1:L
xs = 0 ;
xp = 0 ;
for n = 1: N
for m = 1: M
xs = xs + c(n,m)*exp(-pi*((t-n)./theta)).^2*exp(1i*2*pi*m*(t- n)/M);
xp = xp + c(n,m)*exp(-pi*((t-n)./theta).^2)*exp(1i*2*pi*m*(t- n)/M)*(t-n)^2./theta.^3;
end
end
J = J + ((x_t (t) -xs).*conj (xp));
end
J = -4*real(J);
end
I tested this function using the mfile below.
L = 20;
N = 10;
M = 5;
c =round(10*rand(N,M));
theta0 = 0.96;
x0 = 4;
theta = 0:theta0/(L-1):theta0;
x_t = 0:x0/(L-1):x0;
J = funtc(x_t,c,theta,M,N ,L);
plot(theta,J);
类别
在 帮助中心 和 File Exchange 中查找有关 Matrix Indexing 的更多信息
2018-7-10
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!
Translated by 
