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

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0
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1answer
36 views

using FindRoot to solve 3 simultaneous equations [on hold]

I'm trying to solve 3 simultaneous equations derived from an electrical circuit of a common source amplifier. ...
1
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0answers
29 views

How can I improve the solution of my PDE?

I want to improve the last code to find a better solution for umi. For now I'm using only MaxStepFraction. Also, when I put no ...
0
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1answer
54 views

A question about calculus and Programming

I am a very new user and I would like to know how to calculate the following operations in Mathematica. Honestly this is not a homework. I am an french architect and I would like to be back in Math ...
0
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0answers
50 views

Solving a system of equations using NSolve

I am trying to solve the following system of equations using NSolve, but am running into some problems. Any suggestions ? CASE1 - Facing Problem in Solving the ...
-1
votes
1answer
48 views

Sign of a symbolic expression as a function of parameter values

I need to know the sign of the following expression for p[t] = z/(1-a), as a function of the parameters {a, b, c, z}: ...
0
votes
1answer
54 views

Hill function (equation) vs a gene

So im trying to make one equation equal another to solve for all physically realistic values of $X$. Hill function is: $$ F(X)=\frac{1}{1+(\frac{X}{K})^n} $$ and Gene Z equation is: $$ Z(X) = ...
0
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0answers
28 views

Generating vectors with restrictions on a lattice

Suppose we are given a certain adjacency matrix that contains the information for a given lattice. I want to generate a configuration of vectors that satisfy a restriction. Specifically, if I have ...
1
vote
1answer
40 views

Trying to find solution for system of ordinary differential Equations [on hold]

I've got 2 functions: A'[t] = (0.5/(1 + (B/k1)^n)) - 0.2*A B'[t] = (1/(1 + (A/k2)^n)) - 2*B with conditions of ...
0
votes
0answers
15 views

Recurrent equations [duplicate]

I want to make a relation to show the first 7 elements that don't have the number 7 in it. So far i know how to make it to show the first 7 elements with RecurrenceTable[{a[n + 1] == 7 a[n] + a[n], ...
5
votes
1answer
156 views

Solution to $y = x^x (1-x)^{(1-x)}$ for $x$ [on hold]

Does anyone have any insight to a symbolic Mathematica solution to this equation for $x$ in terms of y? Symbolic of any sort, just not numeric. $$y = x^x (1-x)^{(1-x)}$$
0
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0answers
63 views

How to determine why Solve[] failed?

I don't know what to make of Solve[] failing on this: ...
1
vote
1answer
72 views

How to speed or help Solve[] when it is stuck?

The code below generates a system of equations that I need to Solve[] for {c[5], c[6], c[7], c[8]} in terms of {c[1], c[2], c[3], c[4]}. ...
0
votes
0answers
38 views

NSolve Duration for simultaneous equations solving

At the moment I am asking myself why mathematica gets to point of needing enormous amount of time to solve equations like these when one more "row" or "colum" or both was added in this equations ...
0
votes
2answers
324 views

Does the equation have two roots? [on hold]

I want to solve the equation $$-x^2+\sqrt{2-x^2} \left(x^2+2 x-1\right)+2 x+5=0.$$ I tried ...
3
votes
2answers
96 views

Solve for x given an interpolation function, y

Given a list of data, lst={{x1,y2},{x2,y2},...,{xn,yn}} and the interpolation function fun, y=Interpolation[lst] which ...
3
votes
1answer
93 views

Roots of Whittaker W function

I am interested in finding the roots $u$ of the equation $$ W_{1,\imath b}(a)=0, $$ where $W_{\kappa,\mu}(z)$ denotes the Whittaker $W$ function, $a>0$ is a fixed parameter, $\imath=\sqrt{-1}$ and ...
0
votes
1answer
58 views

Problem using NDSolveValue

Good afternoon, fellas. Could anyone here help me solve this problem? ...
0
votes
0answers
78 views

Finding the numerical solution to a polynomial of a high degree [on hold]

I would like to numerically solve the following equation for ρ and use the obtained values of ρ to calculate the values of VR ...
0
votes
0answers
37 views

How to find points of the external cut of a segment by a nonconvex polyhedron [on hold]

It gives me empty {} when I'm trying to Solve[..]. What's wrong? ...
6
votes
4answers
144 views

How to eliminate variables when using Solve[]

In certain problems, we need to solve systems of equations and get results in terms of just selected variables. For example, how could we solve eqn==0 below for ...
0
votes
1answer
106 views

How to convert a system of parametric equations?

I have a system of parametric equations (t is a parameter) ...
2
votes
1answer
102 views

Solving an integral equation numerically

my problem is: I get the result of definite integral and now I need to find the upper limit for the same integral but with opposite sign value so f2=-f1. ...
4
votes
1answer
145 views

Does `Reduce` give complete and necessary conditions?

I want to obtain a solution for a system of five inequalities. For instance, ...
1
vote
1answer
75 views

Why can Reduce solve for Integers but not for Reals?

I'm showing as an image, since the question is generic. If we remove $m$ from the inequality we get both solutions. Why doesn't the first inequality work for both domains? Edit here is the code per ...
1
vote
1answer
65 views

using FindRoot with a Module that takes a parameter

Observed an error when calling a Module from FindRoot. I created a module which first solves a differential equation and then returns the value of that differential equation when the independent ...
0
votes
0answers
42 views

Solving a nonlinear equation involving convolution

I consider the following functional : $\psi(u,v)= -u(1-v)(1-\alpha k * v) + \epsilon v (\alpha k * v)$, where $k(x)$ is a smooth kernel with $\int |k| = 1$ and $\int k_+ = \alpha \in ]0,1[$, $u(x), ...
1
vote
2answers
78 views

Plotting the solution of a cubic equation against a coefficient in the equation

I have to plot the solution of the following equation against the coefficient $L$. Since it's a cubic equation, I'd like to filter out the real solution first and plot that then. The equation is $L ...
0
votes
0answers
27 views

How to refine the approximate solution of an implicit function? [closed]

I have an equation of the form exp(A(C-x))-1-exp(x-B(C-x)^(2/3))=0 Here A,B and C are constants, x is the unknown, I want to find, but approximate value of x is known. so, the problem is how to get ...
1
vote
1answer
74 views

Is it possible to solve a certain set of nonlinear equations in Mathematica?

I read this question in a Chinese forum last year. At the end of the discussion, they provide a solution of the equations from a C++ program. Unfortunately, they did not get the right answer. ...
0
votes
1answer
58 views

NDSolve issue with initial and boundary conditions

While solving the heat equation in one spatial variable $u_t = u_{xx} $ (x goes from 0 to L) with the initial temperature distribution $T_0 \frac{x(L-x)}{L^2}$ , and with neumann boundary conditions ...
2
votes
1answer
50 views

Plot directional field with a initial vlue

I do not have enough reputation to comment on other questions, hence I have to ask my own one I want to solve the following nonlinear first order ODE, $$(1 + x) (0.5 y[x]^{-0.5} (x - y[x])^{0.5} - ...
0
votes
0answers
41 views

Finding common roots to several functions

I am trying to solve the following problem. Given $a\in\mathbb R^n$, $u\in\mathbb{R}^n$, $m\in\mathbb{N}^\star$, Find the/some common roots $(t_1,...,t_m)$ of the $\frac{m(m-1)}{2}$ ...
2
votes
2answers
80 views

A peculiar behavior of NSolve[]

NSolve[Power[x + 1, x + 1] - Power[x, x + 2] == 0, x, Reals] returns: {{x -> 3.14104}} Great. However, ...
0
votes
1answer
48 views

Symbolically solve system of equations involving matrix

I need to solve the following system of equations symbolically for a_i, b_i, and c_i: ...
1
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0answers
72 views

Can Mathematica Find Closed-Form Solution this Equation

I have tries to solve an equation by using Solve[] to find pl as a function of other variables. However, it generates an Error! Can anyone help? ...
6
votes
0answers
61 views

Strange result of Reduce and ForAll

In the question Can Mathematica tell me if a polynomial has all real roots?, quite a few of interesting answers were given. I wanted to add another one, using quantors, and observed some strange ...
8
votes
5answers
657 views
0
votes
1answer
56 views

Question about the third argument of Solve [duplicate]

I'm learning about derivatives. This is my code: ...
2
votes
2answers
78 views

Study the possible coincidences of the three clock hands hour, minute, and second

Inspired by the very nice problem solutions of the problem of coinciding clock hands, I'd like to extend the question including a "second" hand. While it is obvious that all three hand can coincide ...
3
votes
2answers
297 views

How to solve numerically an equation which contains numerical intergration?

F1[x_] := NIntegrate[E^Sin[y x], {y, 0, 1}] F2[x_] := Log[x] NSolve[F1[x] == F2[x], x] I want to solve the equation, but Mathematica don't solve it. ...
1
vote
1answer
73 views

Solving a complex logarithmic equation

I am trying to solve the following equation for $x$, with integer $n$. (1 - ((-1 + x)^E x^(1 - x) Log[x]^-E)^(1/(-1 + E)))/(-1 + x) == n
0
votes
0answers
57 views
19
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4answers
806 views

Hightlight all the self-intersections of a Lissajous figure

This graph–also known as a Lissajous figure–contains so many self-intersections.How can I highlight them? ...
0
votes
1answer
40 views

Solve and NSolve hitting iteration limit for simple system [closed]

I'm am trying to get Mathematica to determine the intersection of a line and a parabola, like so: Solve[{x + y == 6, x^2 == y}, {x, y}] But evaluating this gives ...
0
votes
1answer
50 views

Question about a catalytic equality?

I have a question on math.SE that explains how I came up with these equations. ...
2
votes
1answer
72 views

Reduce / Solve cannot solve simple equation

Why does Reduce[{a^b*c^b == c, 0 < b < 1, a > 0, c > 0}, c, Reals] give ...
2
votes
3answers
114 views

Find roots of a peak to calculate its width at 10% peak height

I have numeric data points (x,y) values from a peak. I constructed a interpolation to get an interpolating function. Interpolation[data] What I want to do is the ...
0
votes
1answer
36 views
0
votes
1answer
41 views

Recursion depth and solving equations using Solve

I am trying to solve an equation: ...
1
vote
2answers
180 views

How to Fit experimental data with 4D ParametricNDSolve?

Let me first explain the background problem. I'm trying to solve a problem with a projectile motion in 4D such that the position vector is: $\boldsymbol{r}(t)=\boldsymbol{r}[x(t),y(t),z(t)]$ I have ...