# Questions tagged [operators]

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

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### Problems with defining a R(c)-linear operator

My objective is to define an opeartor op such that for every rational function $f(c)$ of a fixed symbol c, $op(f(c) x)=f(c) op(x)$. What is a good way to implement ...
70 views

### Clebsch–Gordan coefficient calculation for L-S basis in system of three particles

I am trying to calculate eq (A3) ...
84 views

### General solution of a differential equation

I'm a beginner in Mathematica and I'm learning about dealing with differential equations but I'm stuck in this problem What I tried to do is I observed that I have the same differential operator ...
183 views

### List[...] + Association[...], or Association[...] + List[...], when does the order matter?

Values of a list can be added to an association's values like so, ...
73 views

### How to define a composition of operators?

If I define P[x]=D[#,x]& (derivative operator) How can I define another operator $Q$ such that $Q(f(x))=Pf(x)+a$ (for example)? Thanks.
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### Symbolic calculations with operator ordering

Given the following set of equations: ...
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36 views

### Taking sums of differential operators

If I define a differential operator: T[i_] := D[#, x[i]] & I am able to apply it multiple times to a function without any issues: ...
209 views

### Finite Differences:

I am having difficulty implementing finite differences in the correct columns of my code. ...
87 views

### Defining custom operators for indexed objects [closed]

I have some symbolic indexed objects $A_i$, $B_{ij}$, $C_{ijk}$, $D_{ijkl}$, etc. I want to define a symbolic differential operator $\partial_{xy}$ that acts on these indexed objects in the following ...
480 views

### Applying several functions to the same argument

Is there a more concise way of achieving the following result (possibly without d |->)? ...
• 21.3k
78 views

### How to define the square root of an operator [duplicate]

How can I define the operator $\sqrt{m^2-\frac{\partial^2}{\partial x^2}}$, such that it acts on the function $\psi(x)$ as follows: \begin{eqnarray*} \sqrt{m^2-\frac{\partial^2}{\partial x^2}}\...
276 views

### Apply central difference formula to a variable twice

I am working with finite difference methods analytically and I would like to be able to perform operations on subscripted variables. I would like to generate the following expression by applying a ...
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277 views

### How can I construct a determinant-type differential operator?

How can I construct a determinant-type differential operator, where the multiplication of elements in the determinant represents the composition of multiple differential operators? \begin{align*} \...
• 217
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### Nested RowBox in MakeExpression reports error when I define my own curl operator, but the single RowBox in MakeExpression works well

I want to define my own vector notation so that the input \[Del] \[Cross] a outputs curl[a] while the ...
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1 vote
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### Confusing abnormalities observed when counting a specific operator in an expression [duplicate]

Recently I have met with some confusing abnormalities when trying to determine if there is a specific operator (usually Plus[] ) in an expression by programming. ...
• 483
87 views

### How to convert an expression of several variables into an operator

Given the expression How can I define the following operator like g[u_, v_] := eq1 The correct definition is
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### How to subtract a list from certain sublists of a list? [closed]

I have a problem in doing an operation on this vector {{2,3},{3,4},{5,6}}-{1,1} I want to minus this to get the result ...
• 369
143 views

### Second order differential operator in Mathematica

I am trying to write the code for the following expression in Mathematica: $$\partial_{x} e^{-g x}=-g e^{-g x}+e^{-g x} \partial_{x}\,.$$ I was able to do so with the help of the following links with ...
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58 views

### How to write the expression for first order differential operator in Mathematica?

How to write the expression for first order differential operator in Mathematica? What I mean to say that I want to evaluate $$\frac{\partial}{\partial x}f(x)=f'(x)+f(x)\frac{\partial}{\partial x}.$$ ...
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98 views

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