Help indexing symbolic ODE in for loop

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Terry Poole
Terry Poole 2021-3-31
评论： Terry Poole 2021-3-31
Ok so my code works,
P = [0; 22.25; 44.5];
syms w(x) v(x)
Dw = diff(w);
Dv = diff(v);
for i = 1:3
% Deflection in y direction
ode_v = diff(v,x,2) == -Izz/(E*den)*(P(i)*(L-x));
cond1_v = v(0) == 0;
cond2_v = Dv(0) == 0;
conds_v = [cond1_v cond2_v];
vSol(x) = dsolve(ode_v,conds_v);
vSol = vpa(simplify(vSol),3)
% Deflection in Z direction
ode_w = diff(w,x,2) == Iyz/(E*den)*(P(i)*(L-x));
cond1_w = w(0) == 0;
cond2_w = Dw(0) == 0;
conds_w = [cond1_w cond2_w];
wSol(x) = dsolve(ode_w,conds_w);
wSol = vpa(simplify(wSol),3)
end
And my output is:
vSol(x) =
0.0
wSol(x) =
0.0
vSol(x) =
1.41e+13*x^2*(x - 3.0)
wSol(x) =
3.14e+13*x^2*(x - 3.0)
vSol(x) =
2.82e+13*x^2*(x - 3.0)
wSol(x) =
6.29e+13*x^2*(x - 3.0)
>>
Which is correct for all 3 load cases,
My issue is, I'm not sure how to call each case, I can't say vSol(1), because it'll assume x=1 and solve the differential equation. So how would I "index" for lack of a better word each case to generate a plot of (v,w) vs. P? I assume since its a syms function that it's not storing these values as an array, honestly it doesn't seem like it's storing them at all.
Any help on how to call vSol(x)(1), vSol(x)(2) and so on would be greatly appreciated.

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采纳的回答

Walter Roberson
Walter Roberson 2021-3-31
wSol{i} = vpa(simplify(wSol),3)
  2 个评论
Terry Poole
Terry Poole 2021-3-31
Error using sym/subsasgn (line 951)
Invalid indexing assignment.
Error in LabSix (line 84)
wSol{i} = vpa(simplify(wSol),3)
Terry Poole
Terry Poole 2021-3-31
ode_w = diff(w,x,2) == Iyz/(E*den)*(P(i)*(L-x));
cond1_w = w(0) == 0;
cond2_w = Dw(0) == 0;
conds_w = [cond1_w cond2_w];
wSol(x) = dsolve(ode_w,conds_w);
wSol = vpa(simplify(wSol),3)
ws{i} = wSol
That did it! Thanks!

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