what should I do. HELP function
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[y, z]=rungeKutta(2,4,0,1,10000)
function dydx=f(x,y,z)
dydx=-2*y + 4*exp(-x) + exp(-1000*(z^2));
end
function dzdx=g(y,z)
dzdx=-y*(z^2)/3;
end
function [y,z]=rungeKutta(y0,z0,x0,xn,n)
h=(xn-x0)/n;
x=x0;
y=y0;
x=x0;
for i=1:n
k0=h*f(x,y,z);
l0=h*g(y,z);
k1=h*f(x+h/2, y+ k0/2, z+ lo/2);
l1=h*g(y+ k0/2, z+ lo/2);
k2=h*f(x+h/2, y+ k1/2, z+ l1/2);
l1=h*g(y+ k1/2, z+ l1/2);
k3=h*f(x+h, y+ k2, z+ l2);
l3=h*g(y+ k2, z+ l2);
y=y + (k0+2*k1+2*k2+k3)/6;
z=z + (l0+2*l1+2*l2+l3)/6;
end
end
采纳的回答
Gaurav Aggarwal
2020-6-26
编辑：Gaurav Aggarwal
2020-6-26
Hi Bilal,
Your code seems to have many undefined variables, like z in line 15, lo in line17, l2 in line 22.
See if the following code works for you and gives the output according to your expectations.
[y, z]=rungeKutta(2,4,0,1,10000)
function dydx=f(x,y,z)
dydx=-2*y + 4*exp(-x) + exp(-1000*(z^2));
end
function dzdx=g(y,z)
dzdx=-y*(z^2)/3;
end
function [y,z]=rungeKutta(y0,z0,x0,xn,n)
h=(xn-x0)/n;
x=x0;
y=y0;
x=x0;
z=z0; %% z added
for i=1:n
k0=h*f(x,y,z);
l0=h*g(y,z);
k1=h*f(x+h/2, y+ k0/2, z+ l0/2); %% lo -> l0
l1=h*g(y+ k0/2, z+ l0/2);
k2=h*f(x+h/2, y+ k1/2, z+ l1/2);
l2=h*g(y+ k1/2, z+ l1/2); %% variable name l1 -> l2
k3=h*f(x+h, y+ k2, z+ l2);
l3=h*g(y+ k2, z+ l2);
y=y + (k0+2*k1+2*k2+k3)/6;
z=z + (l0+2*l1+2*l2+l3)/6;
end
end
Hope it helps. Thanks.
3 个评论
Bilal Ates
2020-6-28
Gaurav Aggarwal
2020-6-28
Did it work for you? If so, it would be great if you accept the answer and close this query. Thanks.
Bilal Ates
2020-6-28
更多回答（1 个）
Steven Lord
2020-6-26
0 个投票
As stated on this documentation page "Script files cannot have the same name as a function in the file." Either rename your script file to something other than rungeKutta.m or rename the function you define on line 9 of rungeKutta.m to something other than rungeKutta.
2 个评论
Gaurav Aggarwal
2020-6-26
编辑：Gaurav Aggarwal
2020-6-26
After defining some variables, the script worked for me. The script's name and the function name were same in my case. As per my understanding, it doesn't matter as long as the function call is within the file scope, which seems to be the case with Bilal's (acc. to the code he provided).
Bilal Ates
2020-6-28
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