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

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2
votes
1answer
111 views

Multiple dynamic equations for plotting?

Say I have a bunch of equations between variables e.g. h=bcd, i=hce, j=ihbd, ...
1
vote
1answer
123 views

Non-linear system of equations with a parameter

I want to solve k*x-(x-y)*y^2==0 and y+(x-y)*y^2-(1-x-y)==0 for -10 < k <10 How ...
3
votes
1answer
127 views

Solving simultaneous systems of linear equations

I have several systems of linear equations in matrix form, and I would like to find the $\vec{x}$ that simultaneously solves them: $$A_1\vec{x} = b_1$$ $$\vdots$$ $$A_n\vec{x} = b_n$$ Is there a ...
7
votes
0answers
139 views

How does Mathematica resolve symbolic systems of inequalities? [closed]

Before getting into my question, let me provide some context: I recently started using Mathematica to automatically perform stability analyses that I previously did by hand. A major part of the ...
3
votes
1answer
287 views

Solving a large system of nonlinear equations

I have a system of 80 nonlinear equations with 64 variables to solve in Mathematica but it takes a lot of time (about two hours) and then it return "no more memory available" knowing that I have 8GB ...
2
votes
2answers
343 views

cycloid parametric [closed]

How do I enter 3 parametric equations for cycloids corresponding to circles with radii 1, 2, and 4. I have tried ...
0
votes
1answer
110 views

How to re-express solution to system of equations after truncating the solution at a given order to give an exact answer

I have a simple enough system of two equations that need to be inverted: ...
0
votes
1answer
231 views

Help Please : Error in plotting the solutions of FindRoot

I want to find the roots of an equation using FindRoot as a function of a real parameter K and then plot the real and imaginary solutions vs. the parameter K. The function I'm trying to find the ...
1
vote
0answers
46 views

Resolve not accepting equations involving factorial

If I take , Resolve[ForAll[x,x!>=0],Integers] True But if I make slight modification, ...
0
votes
1answer
132 views

How to find the Nth zero of a function

It's an almost same question with "a multiple roots finding" but, the order of roots is important in my case. Basically, I'm trying to find Nth crossing point of the following graph: ...
2
votes
2answers
166 views

How to Map each cell in a matrix to another and solve the system?

tab1 = {{a1, a1 + a2}, {b1, b2*b2}} tab2 = {{2, 5}, {5, 2}} I want to map like this ...
0
votes
2answers
99 views

Finding an idiomatic way to express a system of linear equations

I have an $n$ x $n$ matrix $T$, where $t_{ij}$ is the element at the $i\,$th row and $j\,$th column, and unknowns $x_i$, $1\leq i \leq n$, where $$x_{n} = 1$$ $$x_{n-1} = 0$$ $$x_i = \sum_{1\leq j ...
1
vote
1answer
75 views

Missing solutions for complex equation system

I am currently working on a game-theoretic paper and trying to match two complex best response functions. The equation system includes two decision variables x and ...
0
votes
2answers
94 views

Trouble representing an equation

I'm having trouble representing the following as an equation ...
0
votes
2answers
321 views

Simplify trigonometric equation knowing that $\sin(a)=n \sin(b)$

I was working on a problem involving trigonometry. I used Mathematica to help me in solving it. I ended up with this formula: ...
1
vote
1answer
141 views

Why is ((v k)^-n (k v^n - v k^n))/(n - 1) == b so hard for Mathematica to solve (for v)?

I've tried using both Solve and Reduce. For something that takes maybe 3 minutes to solve with paper and pencil, I'm very ...
5
votes
3answers
787 views

Equation is solved quickly using Solve but takes too long using NSolve

I have the following simple command to solve for h in an equation: Solve[(1 - 2.25577*^-5*h)^5.25588 == 0.9644952131579817, h] ...
2
votes
1answer
144 views

FindRoot over a domain, but give domain boundary if no root exists

I call r = x /. FindRoot[f[x] == 0, {x, 0, -5, 5}] f[x] is always monotonic, but sometimes it doesn't have a root in the ...
1
vote
1answer
217 views

Plotting the results of NSolve as Horizontal Lines

Suppose I use NSolve to find the Real approximations to the intersections of two separate functions over some specified range: ...
1
vote
1answer
94 views

Why mathematica is not default set to give real solution, instead of complex one? [duplicate]

N[(-8)^(1/3)] gives 1. + 1.73205 i. Since $(-8)^{\frac{1}{3}}$ has three possible solutions, one real and other two are complex. So, why do not mathematica provides all the three solutions, and if ...
0
votes
0answers
178 views

simulate a 32-bit signed integer overflow in a recurrence function

Considering the following recurring equation: which is this factorial function: I want to find the value of x where f(x) = 0. Actually, the solution is impossible with Mathematica, and it's ...
0
votes
1answer
124 views

How large can be the dimension of a complex matrix which Mathematica can handle to find its eigenalues?

I have been working with 12 cross 12 complex matrix in Mathematica , I need to work with bigger size matrix of the dimension of the order of hundreds , I was wondering if Mathematica can handle ...
4
votes
1answer
259 views

Root finding: zeroes of Mathieu function

I am finding the roots of the Mathieu sine function, and find Mathematica and Maple do not agree on the solutions. For example, consider the solutions of ...
4
votes
1answer
107 views

Solve or preferable Reduce equation

I am new to mathematica and trying to solve and reduce the following: Solve[1 - (1 - p^y)^(u (1 - p)) == a, y] or ...
1
vote
1answer
120 views

Solve for values which produce negative real Eigenvalues?

Given an n x n matrix "A", with one or more unknown parameters, I'd like to show a plot of which values produce stability (negative Eigenvalues). For example, say you have a simple mass-spring-damper ...
1
vote
1answer
58 views

Problems solving a differential equation

I am trying to solve a differential equation: $dN/dt = a*N*(90-N)$ with $N(0)=3$ and $N(11)=43$: Using: ...
2
votes
1answer
74 views

Plotting Multiple Solve Functions

My goal is to plot the functions returned from Solve but assigning each solution to a different function. Here is an example where I do it by hand ...
1
vote
0answers
74 views

Help inteprete the solution given by reduce

I am trying to solve for a2 in the equation below: ...
0
votes
0answers
103 views

Unequal behaviour of FindRoot to two similar functions

Unfortunately, I have some difficulties to plot a function. Here is my code: ...
1
vote
1answer
139 views

handling division by zeros and line equations

today I was writing a code which takes some line equation and a circle equation,finds intersection points that are on $II$ and $III$ quadrants,draw a tangent line to circle from that point and then ...
1
vote
1answer
38 views

problem on returning value of function as a list using if

today i was writing a function for my project using mathematica that gives a line equation in form of $y=mx+b$ and a circle equation in form of $x^2+y^2=r^2$ and finds the intersection point which is ...
1
vote
2answers
164 views

How to solve ArcSinh equation for many differents parameters?

I am totally stuck trying to solve the equation below (1/2) x Sqrt[1 + 4 a^2 x^2] + ArcSinh[2 a x]/(4 a) == d Where a and ...
1
vote
3answers
330 views

High-Precision NSolve

I need to calculate the intersection of two curves f1[x_] := ((Zl ρ ) Exp[-x]) f2[x_] := (α k e^2 /x^2) Where ...
0
votes
0answers
44 views

Problem with solving an equation [duplicate]

I dont understand why Mathematica cannot solve this equation: Solve[Log[x^2 + 5] + 0.5 x + 1 == 0, x] I get this error message: Solve::inex: Solve was unable to solve the system with inexact ...
3
votes
1answer
135 views

Solving a system of generated equations?

I would like to generate a function in the following form, where the number of terms can be specified arbitrarily: ...
1
vote
1answer
209 views

Solving systems of equations

So I have a set of equations like 12 of them but 13 variables. However I would like to find the numerical value of the roots for the maximum value of a particular variable. I don't know how to do that ...
3
votes
4answers
430 views

Solving puzzles with Mathematica

I would like to be able to solve logic puzzles such as the one described here using Mathematica. I have copied & pasted the listed example below to save on jumping about with hyperlinks: The ...
0
votes
1answer
153 views

Manipulate Solve for initial condition

I have a series of $n$ coefficients with parameters $r$ and $b$ that sum up to one. But there i also the initial condition value $c1$ that i required to obtain this normalization. I want to find this ...
0
votes
0answers
42 views

Closed solutions for `FindRoot`, no solutions for `Reduce` or `Solve` [duplicate]

Reduce, Solve and FindRoot all appear to struggle with this: ...
1
vote
0answers
127 views

Using NMinimize to solve the Multi Commodity Flow problem

I have the following optimization problem and I was hoping to solve it with NMinimize. Unfortunately, I don't get the desired result. I would like to get an optimal vector for $d_{e}$. This is how ...
4
votes
2answers
200 views

how to find numerical zeros of $f(z)$ in a compact complex domain

I encountered a function $f(z)$ with several zeros in a region $1<\Re(z)<2, 3<\Im(z)<4$. These zeros are visible in a three dimensional plot like ...
1
vote
1answer
56 views

How do I solve a profile interval (statistics)

I want to calculate a 95% profile interval for f0. Do worry too much if you do not understand what it is. I will illustrate with a simple example. ...
0
votes
2answers
87 views

Plot function the uses Solve

Can someone tell me why I get an error (and how I get around it) from Solve while I try to Plot a function like: ...
7
votes
3answers
207 views

Ovals of plane curves (and esoteric surfaces in space)

Consider the curve $y^2 - x^3 + x=0$ with $x, y$ real. This curve has two connected components (one bounded, one not), and the question is: how do you get Mathematica to tell you that (if you do: ...
2
votes
2answers
217 views

Solving Differential Algebraic Equations as BVP

I am trying to solve a set of DAEs. \begin{equation} -4 \nu (\lambda(s))^{(-1 - 4 \nu)} \theta'(s) \lambda'(s) + (\lambda(s))^{(-4 \nu)} \theta''(s) = -\alpha_y \cos\theta(s) + \alpha_x ...
1
vote
0answers
99 views

Solving an equation for rational modulus 1

I want to solve an system of equations of the form $$\prod_{i=1}^n x_i^{M_{i,k}}=1 \qquad k=1,\ldots,n$$ with complex $x_i$ with constraint $|x_i|=1$ and $M_{i,k}$ integers. This is basically a ...
0
votes
1answer
323 views

How to find all roots of a complex number [duplicate]

Finding all roots, and I know there are four f them, of this (1 - i)^(1/4) Not only real, but imaginary as well
2
votes
3answers
191 views

`Solve` with variables as single vector

Say I have a set of equations where the unknown variables are the elements of a vector $c=(c_1,c_2,\ldots)$ and want to solve it for $c$. Is there a way to do this with ...
5
votes
2answers
1k views

Find all roots in range

Is there any way to check for all roots in a range? Jens' findAllRoots function is pretty good, but runs at approx. 10% of roots missed when I ran a quick check on ...
2
votes
2answers
216 views

Solving 4 variable system of equations

Trying to solve a systems of equations. Here's the code: ...