Questions tagged [equation-solving]

Questions on the analytic and numerical equation solving functions of Mathematica (Solve, Reduce, NSolve, FindRoot, DSolve, RSolve, etc.).

Filter by
Sorted by
Tagged with
2
votes
2answers
51 views

relative accuracy in FindRoot

In my code I have function which takes large value, e.g. y[x_]=10^15 (2 - x^2) When I try to find a root for such function, ...
0
votes
1answer
36 views

Evaluating functions for different values of parameters

here it is my question. I have a system of two equations in two variables, so I can get a solution. The issue is that those equations depend on three parameters, so my solution will depend on their ...
0
votes
0answers
47 views

7X7 matrix of distinct cubed integers with identical row and column sums

Problem: find a 7X7 matrix of distinct cubed integers with identical row and column sums. Well, I have the following code (that came from @kglr from my previous question): ...
0
votes
0answers
25 views

May Rationalize produce a decimal output (do nothing) on results of NSolve, Solve//N?

Here is a perplexing example, which does nothing (yields 0.3) on 11.3, Windows 10: kn = -1 + s 10/3 cr = s /. NSolve[kn == 0, s, 3] Rationalize[cr[[1]]] (my ...
1
vote
2answers
164 views

How to get closed form solution of transcendental equation? [closed]

Transcendental-Equation (closed form solution) I want some method to get closed form solution of a transcendental equation and that is in terms of Lambert's Omega function. The equation $x + e^x = k$ ...
0
votes
2answers
48 views

Having problem in solving hyperbolic functions

I am trying to solve Upm/Um at different points but I am not getting any result. There is any problem with my hyperbolic function? Please help me to get the results. It will be appreciated. ...
0
votes
2answers
78 views

Solving a system of equations using the data generated by PowersRepresentations and ParallelTable

First of all, it is possible to check the code that I am asking for because I know that $x=3051$ must yield at least a solution to the problem. Well, I have the following system of equations: Now, I ...
0
votes
1answer
37 views

Keeping equations in terms of specific variable

I'm new to Mathematica and really struggling with something seemingly simple. I'm trying to do an integration and keep the results in terms of the symbol $T_1$ and $A_i$: $$ T_1=\frac{\text{pi} A_i}{...
2
votes
1answer
71 views

Having error with solving BVP problem

I am trying to solve this differential equation but using my approach: ...
1
vote
1answer
43 views

Automating the solving of system of equations

I checked on the website, and I didn't find a similar topic, so I decided to ask. I solved a couple of maximisation problems, and I obtained solutions for x, y, z and k. What I need to do is to solve ...
0
votes
0answers
43 views

Root finding on Monte Carlo integrals

I have an example function f which is expressed as a Monte Carlo integral as other methods seem to behave even less consistently. The problem with this function is ...
0
votes
1answer
45 views

Solving differential equation in

How to integrate and plot the graph between z vs x, ...
0
votes
1answer
28 views

Why does NSolve give singularities as solutions for this transcendental equation?

I have this (rather long) transcendental equation, that has multiple singularities where it goes to infinity, then reappears at negative infinity. When I try and find the roots of the equation via ...
2
votes
1answer
49 views
2
votes
2answers
72 views

Why is FindRoot throwing a “singular Jacobian” error when function has small values?

Running the code: FindRoot[PolyLog[2, -E^-(10 + Sqrt[1 + x^2])] == 10^-30, {x, 10}] Gives me the error: ...
0
votes
1answer
56 views

Solving equation involving an undefined function

I am new to mathematica and this is my first question, so please forgive me if it is something trivial. I am solving a maximisation problem, and my foc is the following: ...
6
votes
1answer
87 views

Implicit Riccati Equation Solver (to find the anti-stabilizing solution)

I've found that the latest MATLAB icare() solver includes the possibility to find also the anti-stabilizing solution of the Riccati equation. I haven't found a ...
0
votes
0answers
25 views

Finding intersections of points from more than two functions

How to find the intersections of points for more than two functions? Say I have f1, f2, and f3. I don't want to do : ...
8
votes
1answer
248 views

Reusing PARDISO symbolic factorization

Is there a way to do this natively in Mathematica? I read in several places that this is possible with LibraryLink, but I don't have a lot of experience with C and so I'm having trouble implementing ...
0
votes
2answers
45 views

Is it possible to use Reduce in a way that “eliminates” some unwanted variables, and only gives constraints between wanted variables?

Reduce[{x == z, y == z}] gives y == z && x == z but say I'm only interested in constraints that appear between ...
2
votes
0answers
94 views

Finding 36 integer solutions to a set of 14 equations using various boundary conditions

What is good way to solve this system of equations? I have it run now for quite some time and it does not spit out a solution. ...
-1
votes
1answer
35 views

Finding the roots of quintic equation

I want to solve my quintic equation with methods Newton and Bisection , and compare them. And I want to know, how to call Nsolve or Roots and told them that they use only for example Bisection ...
1
vote
1answer
69 views

Solving a system of two equations of cube integers using ParallelTable

Well, I have the following problem: I need to solve the following system of equations: $$ \begin{cases} n=a^3+b^3+c^3\\ \\ n=d^3+k^3+f^3 \end{cases}\tag1 $$ Where: $n\ne a\ne b\ne c\ne d\ne k\ne f$;...
0
votes
1answer
64 views

Integrating FindRoot

I have a certain function F[a_] := FindRoot[f[a,x],{x,0.5}] and I want to compute NIntegrate[F[t],{t,0,1}]. However, ...
1
vote
2answers
61 views

Solving a big system of equations using certain conditions

I have the following problem: I want to solve a big system of equations for a certain number of variables which I call $a_k$, the variables need to satisfy the following conditions: all $a_k\in\mathbb{...
3
votes
1answer
53 views

How to terminating a Do Loop when encounter FindRoot::lstol warning

While finding the roots of a system of non-linear equations, I am encountering the warning "FindRoot::lstol: The line search decreased the step size to within tolerance specified by AccuracyGoal and ...
0
votes
0answers
21 views

Importing data compared with manual data using FindRoot

The code below as written works fine. The problem I am having is that if a replace "dat22" in the line "lhsp = lhs - dat22[[i]];" by "aps" which is a list with the same numbers but obtained from ...
2
votes
3answers
145 views

Problem with Fourier Transform output

I am trying to evaluate this FT, but Mathematica takes long time without output ...
2
votes
2answers
52 views

Approximate solution for ODE

I am trying to find approximate solution for nonlinear ODE(I know there are are ways to do it in mathematica) but I really want why is not working(I modified the code base on some codes suggest by ...
4
votes
2answers
154 views

Why does not ContourPlot provide double roots?

Why ContourPlot does not give double roots? Here is a simple example. ContourPlot[(x-1)^2 (y - 3)^2 == 0, {x, 0, 5}, {y, 0, 6}] If I have a much more complicated ...
5
votes
1answer
99 views

Discrepancy between the results of NDSolve and DSolve (equations related to one step processes)

Bug introduced in 12.0 and fixed in 12.1 The following are the dimensionless equations of a one-step random walk with an "impure" reflecting boundary assuming only four possible states, i.e., n=0, 1, ...
1
vote
1answer
34 views

NSolve and MemoryAllocationFailure

I have a code like, ...
7
votes
2answers
150 views

DEigensystem gives x-dependent eigenvalues

Bug introduced in Version 11 or earlier and persisting through 12.1. Reported to Wolfram Technical Support as CASE:4532301. I am considering the eigenvalue problem associated with the double-well ...
4
votes
1answer
109 views

Trouble with dependent variables in NDSolve while modelling transparent boundary conditions on a quantum graph with Mathematica

I am trying to create a model of plane wave's propagation on a quantum graph(metric graph with a differential operator, Shrodinger operator in my case, along the edges and continuity condition at the ...
2
votes
1answer
92 views

Calculate this Eccentricity of a hyperbola with Reduce

How to calculate the Eccentricity e? $F_1, F_2$ are the left focus and right focus respectively of the hyperbola:$\frac{x^2}{a^2} - \frac{y^2}{b^2} =1$( a > 0 , b >...
0
votes
0answers
42 views

FindRoot not recognising replaced symbol in nested function

I have the following example FindRoot function as part of a Nest function. ...
-1
votes
1answer
47 views

Plane 3D Plotting range values

Below example is equation of a plane example I would know how to determine the range of values for x, y and z respectively. ...
1
vote
2answers
56 views

How to solve an algebraic equation with InterpolatingFunction?

How to solve the equation f[t]==0 for the function f[t] defined by differential equation,i.e. if ...
1
vote
1answer
32 views

Solve a system of equations mixing real and integer variables

I'm trying to solve a system of equations and inequalities with 5 variables but one of them is real, and the other 4 are integer. How could I tell this to Mathematica? I tried using ...
2
votes
1answer
58 views

NCSolve - solve for a variable

I use the latest NCAlgebra package (5.0) for non-commutative algebra. << NC` << NCAlgebra` NCSolve[a**x==b,x] How do I solve for the variable x, ...
0
votes
1answer
56 views

How do I make a function from a solution? [duplicate]

This expression: FullSimplify[Solve[dx == dL - (1/2) dd, dL]] Gives this solution (I've simplified it for brevity): $$\left\{\left\{ d_L\rightarrow \frac{\sqrt{...
0
votes
2answers
65 views

Series can not expand the following root object about infinity. Is there another way to expand it?

I have the following equation which I want to solve it for r: ...
0
votes
1answer
27 views

Use the NSolve function on a list of values

Is there a way to have NSolve loop through a list of values? I know how to use it for single values but unsure if I can get it to loop through a list. I want it to loop through my list of p and have ...
0
votes
1answer
41 views

NSolve produces no solution to a nonlinear system [closed]

This NSolve code on a system of nonlinear equations produces no output: ...
1
vote
0answers
89 views

NDSolve numerical problem

I am trying to solve a couple of differential equations given by: $$F(H(t))=R(\phi(t))$$ $$\phi(t)''+H(t) \phi'(t)+ m \,\phi(t)=0$$ where $m=1$ and $F$ and $R$ are just particular functions. In ...
1
vote
1answer
67 views

I am unable to solve angle of a trigonometric equation

I am fairly new to Mathematica, so this may be a simplistic question, but I want to learn. I know how to use the Solve function to solve a single equation like this: $$\cos[41.614-x]-1.2752|cos[1....
1
vote
2answers
44 views

Plotting a complete response to an oscillation; already have particular solution, not sure how to solve for constants in homogeneous solution

I am writing a code that plots an oscillator's response to a periodic excitation. The response consists of the following: x(t) = xh + xp where xh is the homogeneous solution and xp is the particular ...
3
votes
2answers
99 views

Why Mathematica gives me different results depending on the order I set the parameters when I solve this differential equation?

I am asking Mathematica to solve a differential equation using DSolve, with two different parameters, q and m, and then evaluate at a point. So I write the ...
1
vote
1answer
76 views

How to solve first order complex differential equation?

I want to solve these differential equations and want to get the value of 'a1'. I used this code given below but it is not showing any result. If anyone can resolve this will be appreciated. ...
0
votes
0answers
42 views

Set of multivarible expressions to be re-expressed a single variable

I have a set of expression such as $\frac{3x+y-z}{6x}$ and $\frac{3 x-y+z}{12 x}$, which can easily get re-expressed as $p$ and $(1-p)/2$, where $p=\frac{3x+y-z}{6x}$, but is there a way to find this $...

1 2 3
4
5
91