About solving a system of equations by 'For' loop
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I've written 4 equations within a for loop for 10 steps. But there's the following error:
Attempted to access C(1); index out of bounds because numel(C)=0.
Error in ROW (line 59)
k3=[C(1);C(2);C(3);C(4)];
When I use "double()" for any equation, the answer is not satisfactory for me. I was wondering if you could help me about my problem.
In the following, J1,J2,J3,J4, f1,f2,f3,f4 are knowns.
My currenct script looks like this:
h=1/1000;
y0=[2;2;1;0];
z0=10;
for i=1:10
syms k11 k12 k13 k14 l11
k1=[k11;k12;k13;k14];
eqns = [h*(f1(y0(1),y0(2),y0(3),y0(4),z0)+0.44*(J1(1,:)*k1 +J2(1,:)*l11))-k11==0,
h*(f2(y0(1),y0(2),y0(3),y0(4),z0)+0.44*(J1(2,:)*k1 +J2(2,:)*l11))-k12==0,
h*(f3(y0(1),y0(2),y0(3),y0(4),z0)+0.44*(J1(3,:)*k1 +J2(3,:)*l11))-k13 ==0 ,
h*(f4(y0(1),y0(2),y0(3),y0(4),z0)+0.44*(J1(4,:)*k1 +J2(4,:)*l11))-k14 ==0,
g(y0(1),y0(2),y0(3),y0(4),z0)+0.44*(J3*k1 +J4*l11)==0];
vars = [k11, k12, k13, k14, l11];
[solk11,solk12,solk13,solk14,soll11] = solve(eqns,vars);
A =double( [solk11,solk12,solk13,solk14,soll11]);
k1=[A(1);A(2);A(3);A(4)];
l11=A(5);
syms k21 k22 k23 k24 l21
k2=[k21;k22;k23;k24];
eqns = [h*(f1(y0(1)+E(5)*k1(1),y0(2)+E(5)*k1(2),y0(3)+E(5)*k1(3),y0(4)+E(5)*k1(4),z0+E(5)*l11)+E(11)*(J1(1,:)*k1 +J2(1,:)*l11)+0.44*(J1(1,:)*k2 +J2(1,:)*l21))-k21==0,
h*(f2(y0(1)+E(5)*k1(1),y0(2)+E(5)*k1(2),y0(3)+E(5)*k1(3),y0(4)+E(5)*k1(4),z0+E(5)*l11)+E(11)*(J1(2,:)*k1 +J2(2,:)*l11)+0.44*(J1(2,:)*k2 +J2(2,:)*l21))-k22==0,
h*(f3(y0(1)+E(5)*k1(1),y0(2)+E(5)*k1(2),y0(3)+E(5)*k1(3),y0(4)+E(5)*k1(4),z0+E(5)*l11)+E(11)*(J1(3,:)*k1 +J2(3,:)*l11)+0.44*(J1(3,:)*k2 +J2(3,:)*l21))-k23 ==0 ,
h*(f4(y0(1)+E(5)*k1(1),y0(2)+E(5)*k1(2),y0(3)+E(5)*k1(3),y0(4)+E(5)*k1(4),z0+E(5)*l11)+E(11)*(J1(4,:)*k1 +J2(4,:)*l11)+0.44*(J1(4,:)*k2 +J2(4,:)*l21))-k24 ==0,
g(y0(1)+E(5)*k1(1),y0(2)+E(5)*k1(2),y0(3)+E(5)*k1(3),y0(4)+E(5)*k1(4),z0+E(5)*l11)+E(11)*(J3*k1 +J4*l11)+0.44*(J3*k2 +J4*l21)==0];
vars = [k21, k22, k23, k24, l21];
[solk21,solk22,solk23,solk24,soll21] = solve(eqns,vars);
B =double( [solk21,solk22,solk23,solk24,soll21]);
k2=[B(1);B(2);B(3);B(4)];
l21=B(5);
syms k31 k32 k33 k34 l31
k3=[k31;k32;k33;k34];
eqns = [h*(f1(y0(1)+E(6)*k1(1)+E(7)*k2(1),y0(2)+E(6)*k1(2)+E(7)*k2(2),y0(3)+E(6)*k1(3)+E(7)*k2(3),y0(4)+E(6)*k1(4)+E(7)*k2(4),z0+E(6)*l11+E(7)*l21)+E(12)*(J1(1,:)*k1 +J2(1,:)*l11)+E(13)*(J1(1,:)*k2 +J2(1,:)*l21)+0.44*(J1(1,:)*k3 +J2(1,:)*l31))-k31==0,
h*(f2(y0(1)+E(6)*k1(1)+E(7)*k2(1),y0(2)+E(6)*k1(2)+E(7)*k2(2),y0(3)+E(6)*k1(3)+E(7)*k2(3),y0(4)+E(6)*k1(4)+E(7)*k2(4),z0+E(6)*l11+E(7)*l21)+E(12)*(J1(2,:)*k1 +J2(2,:)*l11)+E(13)*(J1(2,:)*k2 +J2(2,:)*l21)+0.44*(J1(2,:)*k3 +J2(2,:)*l31))-k32==0,
h*(f3(y0(1)+E(6)*k1(1)+E(7)*k2(1),y0(2)+E(6)*k1(2)+E(7)*k2(2),y0(3)+E(6)*k1(3)+E(7)*k2(3),y0(4)+E(6)*k1(4)+E(7)*k2(4),z0+E(6)*l11+E(7)*l21)+E(12)*(J1(3,:)*k1 +J2(3,:)*l11)+E(13)*(J1(3,:)*k2 +J2(3,:)*l21)+0.44*(J1(3,:)*k3 +J2(3,:)*l31))-k33==0 ,
h*(f4(y0(1)+E(6)*k1(1)+E(7)*k2(1),y0(2)+E(6)*k1(2)+E(7)*k2(2),y0(3)+E(6)*k1(3)+E(7)*k2(3),y0(4)+E(6)*k1(4)+E(7)*k2(4),z0+E(6)*l11+E(7)*l21)+E(12)*(J1(4,:)*k1 +J2(4,:)*l11)+E(13)*(J1(4,:)*k2 +J2(4,:)*l21)+0.44*(J1(4,:)*k3 +J2(4,:)*l31))-k34 ==0,
g(y0(1)+E(6)*k1(1)+E(7)*k2(1),y0(2)+E(6)*k1(2)+E(7)*k2(2),y0(3)+E(6)*k1(3)+E(7)*k2(3),y0(4)+E(6)*k1(4)+E(7)*k2(4),z0+E(6)*l11+E(7)*l21)+E(11)*(J3*k1 +J4*l11)+E(13)*(J3*k2 +J4*l21)+0.44*(J3*k3 +J4*l31)==0];
vars = [k31, k32, k33, k34, l31];
[solk31,solk32,solk33,solk34,soll31] = solve(eqns,vars);
C =double([solk31,solk32,solk33,solk34,soll31]);
k3=[C(1);C(2);C(3);C(4)];
l31=C(5);
syms k41 k42 k43 k44 l41
k4=[k41;k42;k43;k44];
eqns = [h*(f1(y0(1)+E(8)*k1(1)+E(8)*k2(1)+E(10)*k3(1),y0(2)+E(8)*k1(2)+E(8)*k2(2)+E(10)*k3(2),y0(3)+E(8)*k1(3)+E(8)*k2(3)+E(10)*k3(3),y0(4)+E(8)*k1(4)+E(8)*k2(4)+E(10)*k3(4),z0+E(8)*l11+E(9)*l21+E(10)*l31)+E(14)*(J1(1,:)*k1 +J2(1,:)*l11)+E(15)*(J1(1,:)*k2 +J2(1,:)*l21)+E(16)*(J1(1,:)*k3 +J2(1,:)*l31)+0.44*(J1(1,:)*k4 +J2(1,:)*l41))-k41==0,
h*(f2(y0(1)+E(8)*k1(1)+E(8)*k2(1)+E(10)*k3(1),y0(2)+E(8)*k1(2)+E(8)*k2(2)+E(10)*k3(2),y0(3)+E(8)*k1(3)+E(8)*k2(3)+E(10)*k3(3),y0(4)+E(8)*k1(4)+E(8)*k2(4)+E(10)*k3(4),z0+E(8)*l11+E(9)*l21+E(10)*l31)+E(14)*(J1(2,:)*k1 +J2(2,:)*l11)+E(15)*(J1(2,:)*k2 +J2(2,:)*l21)+E(16)*(J1(2,:)*k2 +J2(2,:)*l21)+0.44*(J1(2,:)*k4 +J2(2,:)*l41))-k42==0,
h*(f3(y0(1)+E(8)*k1(1)+E(8)*k2(1)+E(10)*k3(1),y0(2)+E(8)*k1(2)+E(8)*k2(2)+E(10)*k3(2),y0(3)+E(8)*k1(3)+E(8)*k2(3)+E(10)*k3(3),y0(4)+E(8)*k1(4)+E(8)*k2(4)+E(10)*k3(4),z0+E(8)*l11+E(9)*l21+E(10)*l31)+E(14)*(J1(3,:)*k1 +J2(3,:)*l11)+E(15)*(J1(3,:)*k2 +J2(3,:)*l21)+E(16)*(J1(3,:)*k3 +J2(3,:)*l31)+0.44*(J1(3,:)*k4 +J2(3,:)*l41))-k43 ==0 ,
h*(f4(y0(1)+E(8)*k1(1)+E(8)*k2(1)+E(10)*k3(1),y0(2)+E(8)*k1(2)+E(8)*k2(2)+E(10)*k3(2),y0(3)+E(8)*k1(3)+E(8)*k2(3)+E(10)*k3(3),y0(4)+E(8)*k1(4)+E(8)*k2(4)+E(10)*k3(4),z0+E(8)*l11+E(9)*l21+E(10)*l31)+E(14)*(J1(4,:)*k1 +J2(4,:)*l11)+E(15)*(J1(4,:)*k2 +J2(4,:)*l21)+E(16)*(J1(4,:)*k3 +J2(4,:)*l31)+0.44*(J1(4,:)*k4 +J2(4,:)*l41))-k44 ==0,
g(y0(1)+E(8)*k1(1)+E(8)*k2(1)+E(10)*k3(1),y0(2)+E(8)*k1(2)+E(8)*k2(2)+E(10)*k3(2),y0(3)+E(8)*k1(3)+E(8)*k2(3)+E(10)*k3(3),y0(4)+E(8)*k1(4)+E(8)*k2(4)+E(10)*k3(4),z0+E(8)*l11+E(9)*l21+E(10)*l31)+E(14)*(J3*k1 +J4*l11)+E(15)*(J3*k2 +J4*l21)+E(16)*(J3*k3 +J4*l31)+0.44*(J3*k4 +J4*l41)==0];
vars = [k41, k42, k43, k44, l41];
[solk41,solk42,solk43,solk44,soll41] = solve(eqns,vars);
D =double( [solk41,solk42,solk43,solk44,soll41]);
k4=[D(1);D(2);D(3);D(4)];
l41=D(5);
y0=y0+E(1)*k1+E(2)*k2+E(3)*k3+E(4)*k4;
z0=z0+E(1)*l11+E(2)*l21+E(3)*l31+E(4)*l41;
end
4 个评论
Walter Roberson
2019-4-8
It appears that I will need f1 function, and J* values, and E values, and possibly some others, in order to run the code to test.
采纳的回答
Walter Roberson
2019-4-8
J1(1,:) is a vector of 4 elements. J2(1,:) is a scalar. When you use both in a single == expression then you are defining 4 simultaneous equations that vary only in J1 values, but you expect that single values of each of the variables will be able to satisfy all of those 4 equations simultaneously. That can only work if the defined equations are degenerate, where the J1 term is being multiplied by 0.
13 个评论
Walter Roberson
2019-4-12
Please post your current code. When I try your code as posted before except with the change to z0 commented out, then it stops at i = 102 with "integer too large in context" because it has reached values that exceed 10 to the three and a half million power.
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