# Questions tagged [operators]

Questions about using or composing operators--functional mappings from one state or vector space to another.

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### Differential operator squared

I defined a one-dimensional momentum operator $\hat{p}=-i\hbar\frac{\partial}{\partial{x}}$ in Mathematica p = -I * h * D[#, x]& and I want to get the ...
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### Can Mathematica Operators be combined in a linear fashion for readability? [duplicate]

Here's a simple example. Suppose we want to find the off-diagonal matrix of m: m={{1,2},{3,4}} This can be solved fairly simply by extracting a list of the ...
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### How to define the Poisson bracket in Mathematica

If $f,g$ are functions of the independent variables $\{q_1, q_2, ..., q_N, p_1, p_2, ..., p_N\}$, then the Poisson bracket is defined as: \begin{equation*} [f, g] = \sum_{i=1}^N \left(\frac{\partial ...
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### custom precedence for custom infix operator with InfixNotation [duplicate]

I am trying to define several custom operators with custom precedence to implement geometric algebra. Loading the notation package << Notation` I can ...
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### Linearity of a function in Mathematica

I have a function which has something like myFunc[q,a state[c,d]] a could be anything, and I want to tell Mathematica that ...
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### HoldForm[Operator ##] on some list

Recently in response to this question Mr.Wizard suggested an unusual way to summing numbers. This doesn't seem to be documented. ...
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### How is + as an infix operator associated with Plus?

How is + associated with Plus? Suppose I want to define a head FooBar and have it ...
185 views

### Displaying the meaning of an operator using Information

I'm using CircleTimes ($\otimes$) operator defined as a_\[CircleTimes]b_ := KroneckerProduct[a, b] so I can use a ESC c* ESC b...
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### when is f@g not the same as f[g]?

I have always thought that f@g will give the same result as f[g] in all cases, and it is just a matter of style which one to use ...
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### Is it possible to define custom compound assignment operators like ⊕= similar to built-ins +=, *= etc?

I would like to do something like this: ...
960 views

### Replace operators

/. can be used to replace variables but how can one replace operators. For example in a * b, ...
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### Definition of differential operators [duplicate]

I am curious how differential operators are defined in Mathematica. More specifically, if the Laplacian function wasn't available, how would one go on to define such a function in Mathematica directly ...
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### How to define the tangent gradient operator? [duplicate]

I would like to define a new differential operator that is the tangent gradient for a curve $\Sigma$. This is defined as $$\nabla_\Sigma=\mathbf{P}\nabla$$ where $\mathbf{P}$ is the projection ...
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### Using D to find a symbolic derivative

I need to do the following: Define a function Take the derivative of this function and have a look at the symoblic representation Substitute in some values With the bonus that I want to use the ...
How do I create an operator which acts like a derivative to everything to the right of it: for example: $\left( \partial_x + \partial_y + z \right ) x \psi$ How do I make that evaluate to: \$x \...