# Questions tagged [symbolic]

For questions about symbolic computation, as opposed to numerical computations.

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### Verify that a PDE is satisfied by a matrix consisting of functions satisfying a different PDE

My problem is as follows: I have two matrices $P$ and $Q$ which are made up of algebraic expressions of a function $q(x,t)$ which solves a somewhat complicated pde, and its derivatives, for example, ...
1answer
84 views

### Symbolic Multivariate Distribution

If I try to input a symbolic multivariate distribution, I do not get a useful result. ...
2answers
172 views

1answer
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### Symbolic non-commutative algebra

Consider 3 non-commutative elements $A,B,C$ and we have the relation $CB=\alpha BC$. I want to compute things like : $(A\otimes BC ) ( B \otimes B) = AB \otimes \alpha B^2C$ Is there any package ...
1answer
46 views

### Rearranging similar terms in an equation

In a piece of code I am writing, I run into an equation of the form ...
4answers
517 views

### Sort with assumptions

I have a list which looks like this list = {0, Subscript[x,7], -Subscript[x,3]-Subscript[x,9], -Subscript[x,9]}; and all the $x_i$'s are positive semidefinite (i....
2answers
71 views

### Identifying total derivatives

I would like to identify which terms in my expression are a total derivative and which ones are not. For expressions in which all terms are a total derivative, one can simply use integrate to find ...
1answer
130 views

### System of coupled differential equations

I am trying to solve the following system of equations, but I get as the output the command itself. ...
1answer
208 views

### Part::pkspec1: The expression j cannot be used as a part specification

I want to do some stuff with symbolic arrays like this a[[j]] + a[[j + 1]] == a[[j - 1]] + a[[j - 2]] But upon declaring such an expression I get ...
0answers
43 views

### On using ConditionalExpression inside Integrate vs. getting the result, then applying Assuming on result [closed]

I thought at first that sol = Integrate[ ConditionalExpression[ integrand, conditions],....] (1) Is equivalent to and should give the same answer as ...
1answer
78 views

### Kronecker Delta manipulation

Is there a way to force mma expressions that have symbolic terms like KroneckerDelta[i,j]*KroneckerDelta[j,k] to simplify to ...
0answers
34 views

### Evaluating Fourier coefficients when Exponential terms are present

I am trying an analytical solution for a 3D Laplace equaition, and just wanted to know if I could use the symbolic calculation capabilities of Mathematica to calculate the Fourier coefficients ...
0answers
28 views

### Linear dependency of vectors of functions

I would like to find a symbolic way to obtain a Q-function (Boolean output) for the following problem. I have the following inputs: ...
1answer
48 views

### Substitution inside an expression [duplicate]

I'm trying to get mathematica to replace an expression with a reduced form. I wanted to replace $(k/w)$ with $h$ in a particular expression, and I've tried something like: ...
2answers
64 views

### Verifying equality

I am trying to test equalities involving integrals. What are the possible causes for not being able to test the following: ...
3answers
92 views

### 3D Plot the result of local Minimize with varying parameter values

I'm faced with the following minimization problem: Find $r\in[0,1]$ that minimizes $\frac{d^2+k^2 (1-2r)r}{2(1-r)r}$, which is bounded by 0 and 1. In addition, $k<d$ holds and each of $d$ and $k$ ...
1answer
46 views

1answer
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### Collecting w.r.t. long expression

Sorry for a probably naive question. I have the following expression ...
1answer
174 views

### Why this PDE causes internal 1/0 division?

Bug introduced in 11.3 and persisting through 12.0.0 In 11.2 DSolve return unevaluated. Assigned WRI case number 4210941 Using 11.3 on Windows 10, this input <...
0answers
83 views

### How to sum over the variable in partial derivative operator?

I need to use the partial derivative operator in Wolfram Mathematica within a summation, specifically to define the D'Alembertian operator of scalar fields. I am having trouble summing over the D ...
1answer
49 views

### Characteristic Function of 2D Gaussian with Boole

Context Given the Probability Distribution ...
1answer
188 views

### Symbolic Neural Networks in Mathematica

Mathematica is very well known about its symbolic capabilities/functionality. Heavy users usually say that “everything is a symbolic expression”. Does this principle apply to neural networks? If not, ...
1answer
74 views

### FindRoot and symbolic evaluation

Following the Symbolic evaluation documentation, I am trying to solve the equation: $y'(x) = a*y(x), \quad y(0)=1$ where I later fix a via FindRoot, requiring that $y(2) = 2$: ...
3answers
84 views

### Evaluating complicated limits correctly

Let's say I have defined some function: a[x_] = x^2 Log[x^2]. If I try to evaluate a Mathematica will complain that it is ...
0answers
70 views

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1answer
79 views

### solving coupled pde with conditions

I have two coupled PDE ...