Questions tagged [equation-solving]

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

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ODE problem using DSolve

I would like to use DSolve (or NDSolve) to verify that the solution to the ODE problem -4(v''[t]+(2/t)v'[t])-2*v[t]*Log[v[t]]-(3+(3/2)Log[4 Pi])*v[t]==0, for $t\...
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0answers
58 views

Can Mathematica solve this exponential equation

My version (12.1.0.0 Student Edition) does not solve this equation: Solve[Exp [-n^2/(2 m)] <= 3/4, m] WolframAlpha finds the solutions, but only for integer n? ...
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37 views

Hi. I'm a beginner so I need help to solve this equations using Regula-Falsi to find root of the equation (which is x)

I've been trying to look for an example but only with one unknown. In my case of studies, I have 4 unknowns. I just want to make sure is it correct the way I'm writing the coding to find the root ...
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2answers
72 views

Why does Solve not solve these two coupled equations?

I have two simple coupled equations eqn1 = 0 == -x + P - G x (y + 1); eqn2 = 0 == -y + G x (y + 1); If I use ...
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0answers
25 views
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36 views
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2answers
82 views

Computing periodic points of some function

Given a function h[{x_, y_}, b_, c_] := {x^2 + c - b*y, x} for some parameter values b and c ...
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1answer
39 views

solving differential equation with matrices

I have to solve two coupled differential equations: ...
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0answers
65 views

Is there an alternative to Reduce that can solve this system of inequalities? [closed]

I try to find the eventual root of a function depending on several parameters. ...
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2answers
84 views

An empty list is generating when I tried to find the roots of transcendental equation using NSOLVE function

I have an equation P which is dependent on ω and γ, and I am trying to find the roots of ω for different value of γ. I have written a small module to carry out this task, but the output of the module ...
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1answer
78 views

Reduce the time to find six integer numbers so that the angle of two vectors equal to Pi/6

I am trying to find six integer numbers a, b, c, x, y, z so that the angle of two vector {a, b, c and ...
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0answers
26 views

Solve Matrix equations with Cross Product: weird system of equations [closed]

I would like to find the values {Pfx, Pfy, Pfz} that satisfy the equation A X B = C . The code of everything is at the end, I want to ilustrate with images what i think of first: A is this: B is this:...
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1answer
44 views

Solving abstract factorization problem with Mathematica

I'm a Mathematica newbie. Given something like: $$(r_0 + r_1 a + r_2 a^2 + r_3 a^5)(r'_0 + r'_1b + r'_2 b^2 + r'_3 b^5) = 1 - a^5 b^5$$ I'd like to determine if there exist $r_i,r'_i$ that solve the ...
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1answer
97 views

NSolve V12.1.1 much slower than V6.0 for the same polynomial system

We are solving polynomial systems with real coefficients using NSolve. A typical system is attached below. The problem we have is that Mathematica V12.1.1 solves it 17 times slower than V6.0, see the ...
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1answer
80 views

Solving an ordinary differential equation with boundary condition at infinity

I want to solve the following differential equation f''[z] + (1/z)*f'[z] - f[z] + f[z]^3 == 0 subject to the boundary conditions $$f^{\prime}(0)=0\qquad\lim_{z\to\...
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1answer
49 views

Numeric solution of ODEs oscillates strongly and stops halfway?

I tried to reproduce the results of a paper. The differential equations are given by ...
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0answers
31 views

can not replace when use ctrl+f

I have a very long output, therefore, I want to find and replace some repeated expressions with abbreviations using crtl +f in Mathematica. when I enter expressions, the mathematical can find it and ...
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2answers
75 views

Forcing mathematica to solve polynomials exactly

It used to be the default behavior that Mathematica would solve polynomials of degree 4 exactly. In the current version I have (12.2.2.0) it sometimes gives numerical answers. Is there a way to change ...
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1answer
41 views

NSolve missing solutions

I'm having trouble solving the transcendental equation. For some values ​​of bi, NSolve obtains 6 roots, however when changing the value, it obtains 5. Graphing the function clearly shows that the ...
4
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2answers
188 views

How can I remove constants from a reduced result?

I am trying to reduce some equations and get the final simplified answer. But there are two issues. This is just an example to show what my problem is. There are lots of similar samples with the same ...
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0answers
48 views

Why doesn't Reduce work?

I try to solve an inequality with parameters using Reduce. The answer i get is : This system cannot be solved with the methods available to Reduce. Here is the inequality: ...
3
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1answer
57 views

Solve yields complex Root even if the domain is Reals

I want to solve $x^3=a^2$ for $x$ where $a>0$ and $x$ is real. The answer I want is $$x=a^{2/3}.$$ On Wolfram Cloud, I tried ...
1
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1answer
41 views

Numerically obtaining roots as a function of another variable

I have an equation $f(x,y) =0$ that Mathematica can solve numerically using NSolve for a fixed $y$. I want to perform the following operation: ...
0
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1answer
60 views

Solve equation system for expression [closed]

How to solve this equations and find specified expression (all integers)? x * N + y = 2012 y * N + x = 2011 x + y = ? I've tried but got formulas as an answer ...
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0answers
31 views

Solve coupled equations in the steady state

I want to solve 16 coupled differential equations in the steady state. Among the answers, I only require two of the answers. But the Mathematica does not show me the answers in detail!!! Can anybody ...
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1answer
39 views

Matching polynomial coefficients when solving an equation

Two polynomials of the same degree are equal if the they have the same coefficients. I would like to use that to find all coefficients of a polynomial: ...
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1answer
37 views

Solve gets stuck with rater simple algebraic equation

Solve[(a^(1/4) + c^(5/3) x)^(6/5) == b && a > 0 && b > 0 && c > 0, x, Reals] is running forever. Why?
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1answer
33 views

Solve equation with four variables [closed]

I am trying to solve the following equation with mathematica $0 = \frac{(2n+1)}{w^2} + \frac{(2n-1)}{w^2}x^2 + 2\frac{z}{y}\frac{x}{w}$ where $n$ is just a positive integer. So I used the following ...
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1answer
43 views

3D plot using Table & FindRoot

I have two expressions involving terms $S_1$ and $S_2$, call the expressions $F1, F2$. I cannot solve $F_i=1$ for $S_i$ so instead I numerically approximate using ...
1
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1answer
55 views

Modulus option quietly nerfed for Solve?

Recently asked my students to put together something like this: Reduce[x^2 ==b, b, Modulus -> 11] For me, on 12.1, this gives: ...
3
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2answers
99 views

Finding the coefficients of an expression

I have a set of formulas of the following form: ...
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0answers
50 views

Solving these set of equations with complex parameters

For $\{a,b,c\}\in \mathbb{C}$ and $\{\gamma,N\}\in \mathbb{Z}^+$, I have an equation ...
5
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3answers
350 views

My evaluation is taking a lot of time

I was evaluating the roots of a transcendental equation, when I noticed that Mathematica never finishes but stays in the running state. The following is the code that I was using: ...
4
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4answers
451 views

Finding the “least” singular solution for NDSolve

I need to solve a ODE for a function $f_\sigma(x)$, where $\sigma$ is a free parameter to tune. All the solutions are supposed to be singular for some value of $x$, except one for a given value $\...
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1answer
46 views
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1answer
48 views

Conically shaped pit

I need help with b. I tried to use the find root but it didn't work !
2
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1answer
88 views

Why Mathematica is returning a complicated output rather than a simple one (as in the screenshot) [closed]

I am using Nsolve to get output on my thread of equations. I have two screenshots attached here. I was supposed to get the same result as pic#1, rather than pic#2. Can someone help me with how can I ...
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4answers
512 views

Find zeros of a transcendental function

Mathematica 10 can not give me solution of this equation ...
2
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2answers
91 views

Does a positive real solution exist to this problem?

I wrote the following code for getting the solution. I am not sure if the code I wrote is correct. The problem is further intensified by the fact that I don't know if a solution exists to this problem ...
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0answers
40 views

Solve gives an empty output

I want to solve the following system, but it gives me an empty output: ...
0
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1answer
106 views

Solve Equation trinomial Nine degree!

I am trying to solve equation: x^9+p*x^4−q==0, {p, q} ∈C using functional analysis. Ηow do I solve this equation and with help Mathematica program for case p=π, q=...
2
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4answers
484 views

How to fix problems solving for values of BSpline function?

I generated a spline function called f using the BSplineFunction with domain {t, 0, 1}. <...
1
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2answers
117 views

How to get rid of imaginary part in cubic root

When I try to solve the following cubic equation for $a$ on mathematica : S=Solve[a^3 - 4 x - 2 a^2 x + 8 x^3 + a (- 6 - 4 x^2) == 0,a]; I get a complex expression ...
4
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1answer
188 views

DSolve returning InverseFunction while I believe the answer isn't so complicated

I was trying to solve the following differential equation: $$A'(y)^2 = -\frac{1}{l^2} e^{-2A(y)} + \frac{1}{L^2}.$$ I know that one possible answer is $$A(y) = \log\left( \frac{L}{l}\cosh\frac{y}{L}\...
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0answers
52 views

Solve not giving a solution for given variables

Solve is not giving me a solution for the following: ...
7
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1answer
154 views

Running Mathematica in 'SpouseMode'

In this previous question I looked into a deprecated capability of Mathematica from Version 2. Mathematica command that allows it to read my intentions Thanks to all for your answers. I note that ...
1
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1answer
35 views

How can I solve equations by matching prefactors?

I have complicated expressions involving traces, for example tr[a], tr[a^2], tr[a]^2, ...
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0answers
37 views

NSolve with ParametricFunction

I have solved a SDE with ParametricNDSolve: s = ParametricNDSolve[ {p1, m1, p0, m0}, {P, m}, {r, 0, 1}, {m, k, e, Cnew} ] And now I want to treat the ...
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0answers
43 views

NDSolve gives error with solving given equation [closed]

I need to solve differential equation, but I am not sure what is wrong with it, because Mathematica does not want to solve it and gives me ...

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