Continuing Matrix involving a function to make very large

2020 6 17
1 个回答
更新时间：2020 6 17
3 次查看（30 天）

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Hi all, i have a typed square matrix and need to expand it to be very large how ever this will take far too long to do manually. my matrix code is below please help if you know any function to expend it while keeping the same pattern.
thanks in advance
syms e P n
c=1;
G(n)=e/(2*(P+0.5*(1i*n*c)-(0.25*(n)^2)));
j=[1 0 G(7) 0 0 0 0 0 0 0 0 0 0 0 0;0 1 0 G(6) 0 0 0 0 0 0 0 0 0 0 0; G(5) 0 1 0 G(5) 0 0 0 0 0 0 0 0 0 0; 0 G(4) 0 1 0 G(4) 0 0 0 0 0 0 0 0 0; 0 0 G(3) 0 1 0 G(3) 0 0 0 0 0 0 0 0; 0 0 0 G(2) 0 1 0 G(2) 0 0 0 0 0 0 0; 0 0 0 0 G(1) 0 1 0 G(1) 0 0 0 0 0 0 ; 0 0 0 0 0 G(0) 0 1 0 G(0) 0 0 0 0 0; 0 0 0 0 0 0 G(-1) 0 1 0 G(-1) 0 0 0 0; 0 0 0 0 0 0 0 G(-2) 0 1 0 G(-2) 0 0 0; 0 0 0 0 0 0 0 0 G(-3) 0 1 0 G(-3) 0 0; 0 0 0 0 0 0 0 0 0 G(-4) 0 1 0 G(-4) 0; 0 0 0 0 0 0 0 0 0 0 G(-5) 0 1 0 G(-5); 0 0 0 0 0 0 0 0 0 0 0 G(-6) 0 1 0; 0 0 0 0 0 0 0 0 0 0 0 0 G(-7) 0 1 ];

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回答（1 个）

Ameer Hamza
Ameer Hamza 2020-6-17

0 个投票

Try this
syms e o n
c=1;
P = 1;
G(n)=e./(2.*(P+0.5*(1i*n.*c)-(0.25*(n)^2)));
N = 15;
l_start = 5;
u_start = 7;
l_end = l_start-N+3;
u_end = u_start-N+3;
j = diag(ones(1,N)) + diag(G(l_start:-1:l_end), -2) + diag(G(u_start:-1:u_end), 2);

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