Questions tagged [symbolic]

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

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votes
1answer
90 views

Symbolic multiplication of tensors

I am trying to do symbolic calculations on Pauli Matrix Algebra. I want to find some way of making CircleTimes[a,b] ** CircleTimes[c,d] map to CircleTimes[a.c,b.d] for every a,b,c,d. I would also like ...
0
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1answer
40 views

unexpected Transpose::tperm error [on hold]

I am trying to use Transpose on the two lists of same length: Mathematica code is ...
2
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1answer
100 views

Evaluating an integral symbolically

I am trying to integrate following integral symbolically via integrate command: $$(0.09)\Bigg[1 + \Bigg\{ \int_{3t-4k-7}^{2k+7/3} (0.09) \text{exp}\Bigg(\int_{3s-...
0
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0answers
56 views

Reduce, Solve, RSolve for symbolic equations? Neither seems to work for my problem

I want to solve the followiwng system of equations: Through substitution I get: I want to solve this equation for P_t I tried the following: ...
0
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3answers
88 views

How can I calculate the expected value of the sum of “n” i.i.d. variables with any distribution?

Particulary, I would like to find the expected value of the sum of $n$ variables distributed like ParetoDistribution[1,1.14]. For example, this works for the sum of two vars with Gamma distribution: <...
2
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0answers
58 views

Trace function did not show the steps to the final answer

Trace[ FullSimplify[ 1/4 Sec[20 °] + Sin[10 °] + 2 Sin[10 °]^2 ] ] Mathematica gave the correct answer 1/2, but it did not show the final steps to arrive at 1/...
5
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2answers
368 views

Turning arguments into exponents

I'd like to replace every instance of L[stuff], e.g., L[-1,-2,-2] in an expression with ...
1
vote
2answers
90 views

Coefficient of power $p$ in polynomial expansion : Mathematica doesn't answer me

I would like to compute the coefficient in front of $n^p$ for a polynomial expansion. I wrote the following code: ...
2
votes
2answers
109 views

Is there a way to know which symbolic expression Mathematica used?

Take the following symbolic sum: Sum[(-1)^n/Factorial[2*n]*(Pi/2)^(2*n)*n, {n, 1, Infinity}] Mathematica answers me: $- \frac{\pi}{4}$ It is great, I have an ...
0
votes
1answer
44 views

Subscript and superscript symbols for chemical calculations

I have some very unhandy, big equations which contain quantities like $n_{AB}(^{13}C)$, now i would like to adapt this notation also in Mathematica so I do not need to think of a new one. Is there a ...
0
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1answer
42 views

Reducing or solving a simple linear equation problem

I have the following equations ...
2
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0answers
33 views

Symbolic formula from GeometricScene?

I'm trying to solve the following problem with GeometricScene What is the shortest circular arc of which the altitude above its chord is one? I have the following code: ...
10
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2answers
536 views

Make symbols atomic, without losing their type

So, I'd like to define a matrix M, that does not decompose into it's constituents when I do things like Tr[M], but I also want it's type to be retained. (By type, ...
0
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0answers
62 views

Limiting solution space for symbolic algebra problems

I have a system of 12 quadratic equations with 12 variables (x11, x12, x21, x22, x23, x33, p1, p2, p3, ϕ, μ, τ) and several positive constants,w, q1, q2. ... > 0<...
4
votes
1answer
91 views

Triggering WhenEvent as a result of WhenEvent

I'm attempting to solve a dead-simple differential equation with events: ...
2
votes
1answer
99 views

Problem when solving differential equation [closed]

Can anyone tell me why do I have errors when I try the code below ? ...
0
votes
3answers
70 views

Expand and Simplify do not work for NonCommutativeMultiply

Expand and Simplify do not work for NonCommutativeMultiply[] then how do we expand an expression like (a+b)**(a-b) ?
2
votes
1answer
45 views

Is there a method to preserve order when matrix multiplying in Mathematica?

I know that commutativity can be preserved in Mathematica by using ** i.e. a*b can get printed as b a but if I use a**b then it will always be printed as a b. However, I am not able to implement ...
0
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1answer
49 views

Symbolic derivation of LU

I've been needing to derive some LU factorizations by hand, analytically, and i was wondering if anyone knew if it were possible to get Mathematica to do this symbolically so that I may be able to ...
1
vote
1answer
70 views

Small error on symbolic eigenvalue of $2\times2$ matrix

I have some computation where I specifically define a 2x2 matrix to have a specific eigenvector v associated with an eigenvalue g, and a second eigenvalue l : ...
0
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1answer
38 views

I am asserting a variable in Mathematica as Real yet it is not implementing it!

Element[\[Theta], Reals]; Ga = g; Gb = g*Exp[I*\[Theta]]; {{Conjugate[Gb], Ga}, {Ga, Gb}} I have a code as such for a matrix as given above. as ...
0
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1answer
38 views

Symbolic Resultant Too Slow/Keeps Running

Evalutation of the following cell, which includes the symbolic resultant, of two univariate polynomials in $x$, with parameters $a,b,c$ for the first polynomial (of degree 4) and parameters $d,e,f,g$ ...
2
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1answer
33 views

Construction of symmetric function / matching function argument patterns

[Edited for clarification after comment] Suppose that the function f is defined as the linear combination of several translated/reflected functions starting from the primitive f0[x,y,z] ...
4
votes
2answers
120 views

Solving symbolic equation for fraction of variables

Suppose there is an equation like this (overly simplified example): eqn1 = ui - ua r1 / (r1 + r2) == 0 How can I get Mathematica to "solve" the equation in terms ...
1
vote
1answer
28 views

How to change the form of the answer? [duplicate]

Reduce[x^2 + y^3 == z && x + 2 y == 3 z + 1 && x y z != 0, {x, y, z}] you get ...
1
vote
1answer
73 views

How to speed up the calculation of a multi-dimension matrix involving symbolic integral?

The following program succeeds in getting matrix CC, but it takes time badly, especially in the case varNumber becomes larger just as the following ...
2
votes
1answer
81 views

Unstable symbolic expectation of gaussian distribution on absolute values?

Context I use mathematica 11.3 and 12. 11.3.0 for Mac OS X x86 (64-bit) (March 7, 2018) 12.0.0 for Mac OS X x86 (64-bit) (April 7, 2019) I am interested in evaluating the following integral ...
0
votes
1answer
27 views

TensorReduce causes “inhomogeneous dimensions” error

I want to use TensorReduce to realize the following property of wedge: ...
1
vote
1answer
73 views

How to pass lists as arguments in NMinimize or FindMinimum?

The following code runs in Mathematica 12. But, I have two problems that I would like to solve: (1) How to pass a list as an argument to the function g in such a way that it can be used seamlessly ...
0
votes
1answer
56 views

Multiple Assumptions for Symbolic Matrices

new to the forum and here's the question I'm pondering on: I'm trying to use FindInstance in Mathematica to solve a symbolic matrix equation with quite a few assumptions. For example, quite ...
2
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0answers
54 views

Issues with symbolic integration

I am trying to do the following indefinite integral, ...
4
votes
3answers
241 views

Alias for root of a polynomial

I need to work with a variable $u$ such that $u^2 + u + 1 = 0$. I don't want to find a root of the polynomial $u^2 + u + 1$. Rather, I have to work with $u$ symbolically so that a (polynomial) ...
4
votes
0answers
85 views

Can I use Mathematica ML capability to translate an image of a formula?

If I am given a pdf image of a mathematical symbolic formula can I translate it into Mathematica syntax using ML? I tried using Classify, but I can only translate parts of the equation and I don't ...
20
votes
2answers
2k views

Wrong answer from DSolve when solving a differential equation

Bug introduced in 12.0.0 I was trying to solve the following differential equation: $$\frac{dy}{dx}=x^2+y^2-1 \quad \text{and} \quad y(0)=1$$ and I used the code below: ...
5
votes
0answers
67 views

Can I extract symbolic expression of neural network loss function?

Once we create a neural network with NetChain in Mathematica, can we extract the loss function in the symbolic form for Mathematica to play with symbolic manipulations using Mathematica's built-in ...
1
vote
1answer
29 views

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, ...
2
votes
1answer
84 views

Symbolic Multivariate Distribution

If I try to input a symbolic multivariate distribution, I do not get a useful result. ...
5
votes
2answers
164 views

Solving a heat equation problem

I'm brand new to Mathematica. I am trying to solve a heat equation problem, but I keep getting back the input on the output line. The problem: Consider the equation $\qquad u_t = u_{xx} - 9 ...
2
votes
0answers
32 views

How to Simplify/Factorise symbolic non-commutative expressions?

It always strikes me as odd, that Mathematica seems to have a hard time with non-communative multiplications. I can use the horrible TensorExpand (or more performant Distribute) to get ...
3
votes
0answers
110 views

Evaluate $\int_0^1 \frac{\log \left( 1+x^{2+\sqrt{3}}\right)}{1+x}\mathrm dx$

Saw this post and noted that it was posted back in 2013. Just tried V11.3 and got no analytic solution. Just wondering if there is a way for Mathematica to give the desired result? Machine VS Human ...
2
votes
0answers
119 views

Substitution of expressions using Groebner basis

I know this topic came up numerous times (most of the results are detailed in the comments of this link Is there a way to to substitute for symbols, simplify, and back-substitute?). However, I have ...
1
vote
1answer
91 views

Definite Integration by parts

how do I code Integrate[u[x] D[v[x], x], {x, a, b}] to return the following straightforward undergraduate result? ...
1
vote
1answer
24 views

Trying to apply Jensen's inequality to a complicated symbolic expression

I have a somewhat complicated inequality expression like this: ...
0
votes
2answers
43 views

How to manipulate sequences of inequalities?

I am trying to write some symbolic inequality proofs in Mathematica. What would be a clean way to make the inference that a >= b and ...
1
vote
0answers
40 views

Finding symbolic solution to constrained optimization question

The code below is my attempt to solve a constrained optimization problem: ...
5
votes
1answer
1k views

Vector calculus integration identity problem

This is a follow up from another post. I was using the integration symbols available in the Basic Math Assistant palette. I am new to vector calculus operations. There is a known identity found in ...
1
vote
1answer
49 views

DSolve returns unevaluated

I am trying to find a solution to this system of differential equations but the program gives the same output without any messages. I would like help. Please find the Mathematica code posted here: <...
1
vote
1answer
105 views

Mathematica doesn't extract Re and Im parts properly

I have a code: ...
2
votes
0answers
77 views

Asymptotes of parabolic cylinder differential equations with boundaries at infinity

For context, I'm studying the paper Coulomb blockade in superconducting quantum point contacts by Averin from 1998. Specifically, I am trying to find how he obtains equation 11 from equation 10, which ...
3
votes
0answers
55 views

Problem solving first order ODE's with DSolve

The issue I am facing is the following. I am trying to solve a system of two coupled first order ODE's with DSolve: ...