When is the Jacobian of a function a diagonal matrix

In summary, the conversation discusses finding the Jacobian J(f) of a function f(x,y,z) and determining when the Jacobian J(g) of a function g(x,y,z) will be a diagonal matrix. The Jacobian J(f) is found to be a diagonal matrix with the component functions exp(x), cos(y), and sin(z). It is suggested that the presence of zeroes off the diagonal in the Jacobian is determined by the component functions of the function in question.
  • #1
ak123456
50
0

Homework Statement


Let f(x,y,z)=(exp(x),cos(y),sin(z)).Compute the Jacobian J(f) of f . In general ,when will the Jacobian J(g) of a function g(x,y,z) be a diagonal matrix ?


Homework Equations





The Attempt at a Solution


I am not quiet sure about this question
for J(f) i found that
(e^x 0 0)
(0 -siny 0)
(0 0 cosz)
and i think this is already a diagonal matrix
 
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  • #2


Your Jacobian looks fine to me. The second question was "In general ,when will the Jacobian J(g) of a function g(x,y,z) be a diagonal matrix ?"

What was it about the component functions that gave you all those zeroes off the diagonal?
 

Related to When is the Jacobian of a function a diagonal matrix

1. What is the Jacobian of a function?

The Jacobian of a function is a matrix of partial derivatives that represents the rate of change of a vector-valued function with respect to its variables. It is an important tool in multivariable calculus and is used to solve problems involving optimization, curve fitting, and differential equations.

2. When is the Jacobian of a function a diagonal matrix?

The Jacobian of a function is a diagonal matrix when the function is a transformation that only affects one variable at a time. This means that the function is not coupled with other variables and can be easily inverted. In other words, the partial derivatives with respect to all but one variable are equal to zero.

3. How do you determine if the Jacobian of a function is a diagonal matrix?

To determine if the Jacobian of a function is a diagonal matrix, you can calculate the partial derivatives of the function with respect to each variable and see if they are all equal to zero except for one. Alternatively, you can also check if the Jacobian matrix is a square matrix with non-zero elements only on the main diagonal.

4. What is the significance of a diagonal Jacobian matrix?

A diagonal Jacobian matrix indicates that the function is not coupled with other variables and can be easily inverted. This makes it easier to solve problems involving optimization, curve fitting, and differential equations. It also simplifies calculations and makes it possible to perform certain transformations on the function.

5. Can the Jacobian of a function be a diagonal matrix in higher dimensions?

Yes, the Jacobian of a function can be a diagonal matrix in higher dimensions as well. In fact, it is much more common for the Jacobian to be a diagonal matrix in higher dimensions as there are more variables that can be uncoupled. This allows for more complex transformations and calculations to be performed on the function.

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