Calculation of the divergent rotational of a function in Matlab

Question

I have a college job where I have to create a routine to calculate the divergent rotational of any function in Matlab.

Researching, I found that I can use the function divergence() to calculate the user-imputed vector divergent.

I started the code:

clc 
clear

%Calcular o divergente da função

i = input('Insira o vetor i: ');
j = input('Insira o vetor j: ');
k = input('Insira o vetor k: ');

div = divergence(i,i,k);
printf(div);

When I insert some letter in the question, it returns the error below (put "2x"):

"Error using input Undefined Function or variable 'x'."

When I just enter numbers, I can get to the part where I calculate the divergent, but it makes that mistake:

"Error using divergence (line 54) U,V,W must all be a 3D arrays."

I would very much like your help, if possible!

Simply recalling that the divergent is calculated by the partial derivative of i in relation to x, j in relation to y and k in relation to z.

Answer 1

You have two options here.

To be using 2*x is necessary to symbolic function of MATLAB.

If this is the case, you can use this direct example to help:

syms x y z; divergence([x^2 2*y z], [x y z])

If you want to use the same function but with the numeric mode, the setting is a little more complex and requires 3D matrices (reason for the error), generated using the meshgrid or with its function to define the 3D space.