How to find gradient of a vector field in matlab symbolic

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Chandan
Chandan 2023-12-12
回答： Chandan 2023-12-13
I am trying to find gradient of a vector field in matlab symbolic , whose output will be matrix but it am getting error
  2 个评论
KSSV
KSSV 2023-12-12
Copy your code here. Don't attach it as an screen shot/ image.
Chandan
Chandan 2023-12-12
Ran in:
clc ; clear all
syms x y z
syms u(x,y,z) v(x,y,z) w(x,y,z)
V = [u v w];
S = [x y z];
gradient(u,S)
ans(x, y, z) = 
gradient(V,S) % How to take gradient of vector field
Error using sym/gradient
Invalid argument at position 1. Argument must be scalar or a symbolic function with scalar formula.

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采纳的回答

Walter Roberson
Walter Roberson 2023-12-12
移动：Walter Roberson 2023-12-12
Ran in:
The fundamental problem you are having is that gradient does not accept a vector the first parameter.
syms x y z
syms u(x,y,z) v(x,y,z) w(x,y,z)
V = [u(x,y,z) v(x,y,z) w(x,y,z)];
S = [x y z];
temp = arrayfun(@(EXPR) gradient(EXPR,S), V, 'uniform', 0);
result(x,y,z) = [temp{:}]
result(x, y, z) = 

更多回答（2 个）

Sulaymon Eshkabilov
Sulaymon Eshkabilov 2023-12-12
Ran in:
If you assign an expression for V, you will get this:
clc ; clearvars
syms x y z
syms u(x,y,z) v(x,y,z) w(x,y,z)
V(x,y,z) = 2*u+3*v-w % Some e.g. expression
V(x, y, z) = 
S = [x y z];
du = gradient(u,S)
du(x, y, z) = 
dV = gradient(V,S)
dV(x, y, z) = 
% OR simply
dV= gradient(V,[x,y,z])
dV(x, y, z) = 
Chandan
Chandan 2023-12-13
Ran in:
% thanks for answer. It worked with the Jacobian too.
clc; clearvars;
syms x y z
syms u(x, y, z) v(x, y,z) w(x,y,z)
V = [u v w];
S = [x y z];
jacobian(V,S)
ans(x, y, z) = 

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