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Subs function doesn't fully replace the values

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Roberto Toledo Fdez-Cañaveral
评论： Roberto Toledo Fdez-Cañaveral 2024-4-17
I'm testing the subs function and I was wondering why when I use a sin or cos, I don't get the numeric value and instead get this longer version. Also, will it keep getting bigger and bigger if I keep working with that matrix? Here's the code I'm using:
syms X Y Z W
q = [X, Y, Z, W];
q_1 = [1, 2, 3, 4];
phi = [(2*X-W)^2 X^2-2*Y Y*sin(Z)];
J = jacobian(phi,q);
disp(J);
J_1 = J;
J_1 = subs(J, q, q_1);
disp(J_1);
And here it is what is shown in the displays:
[8*X - 4*W, 0, 0, 2*W - 4*X]
[ 2*X, -2, 0, 0]
[ 0, sin(Z), Y*cos(Z), 0]
[-8, 0, 0, 4]
[ 2, -2, 0, 0]
[ 0, sin(3), 2*cos(3), 0]

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采纳的回答

VBBV
VBBV 2024-4-16
Ran in:
syms X Y Z W
q = [X, Y, Z, W];
q_1 = [1, 2, 3, 4];
phi = [(2*X-W)^2 X^2-2*Y Y*sin(Z)];
J = jacobian(phi,q);
disp(J);
J_1 = J;
J_1 = subs(J, q, q_1);
disp(double(J_1));
-8.0000 0 0 4.0000 2.0000 -2.0000 0 0 0 0.1411 -1.9800 0

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