Tagged Questions

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

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1
vote
1answer
45 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
52 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
78 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 ...
2
votes
0answers
56 views

How does Mathematica resolve symbolic systems of inequalities?

Before getting into my (probably annoying) question, let me provide some context: I recently started using Mathematica to automatically perform stability analyses that I previously did by hand. A ...
0
votes
0answers
47 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
0answers
38 views

Solve 3 equations

I want to solve for $f, F$ and $\phi$ with these 3 equations: $\left\{m v=m f \cos (\theta )+M F \cos (\phi ),m f \sin (\theta )=M F \sin (\phi ),m v^2=m f^2+M F^2\right\}$ How could this be done?
2
votes
1answer
110 views

Catastrophic loss of precision

while I am trying to solve the double integral in the range of 0 to Infinity (for both the integral) it give me the error Catastrophic loss of precision in the global error estimate due to ...
2
votes
2answers
105 views

cycloid parametric [on hold]

How do I enter 3 parametric equations for cycloids corresponding to circles with radii 1, 2, and 4. I have tried ...
0
votes
1answer
50 views
1
vote
0answers
30 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
31 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
141 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
0answers
20 views

batch processing proof of the number of jobs' relationship with service time and waiting time [closed]

The classical batch processing system ignores the cost of increased waiting time for users. Consider a single batch characterized by the following parameters: M average mounting time T average ...
0
votes
1answer
61 views

Plotting and Analysing derivatives of solution of differential equation [closed]

Using NDSolve I found the solution for the differential equation that governs the dynamics of a simple pendulum. How do I plot the derivatives of the solution? Also, I would like to find the ...
0
votes
2answers
82 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
47 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
61 views

Trouble representing an equation

I'm having trouble representing the following as an equation ...
0
votes
1answer
61 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: ...
0
votes
0answers
52 views

Solve unable to interpret set of equations [closed]

I have Solve[(7*h^2+10*h+7)*(a*h^2+b*h+c)==(33*h^2+8*h-14),{a,b,c}] for which Mathematica returns partial answer which is actually not useable. Even by hand I ...
-1
votes
0answers
23 views

Niven's corollary equations in division ring [closed]

Please proof corollary of Niven: For $a \in D\backslash R$, the equation ${t^n} = a$ has exactly $n$ solutions in $D$, all of which lie in $R\left( a \right)$, in there $R$ is a real-closed field and ...
1
vote
1answer
101 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
210 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] ...
1
vote
2answers
50 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: ...
0
votes
0answers
57 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 ...
1
vote
1answer
63 views

solve recursive factorial function [closed]

Is there a way to solve this recursive factorial function? a[n + 1] = (n+1)*a[n], a[10]=10 I am looking for the value of a[n] ...
0
votes
1answer
58 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 ...
0
votes
0answers
32 views

Zero of a function [migrated]

let $$F(x)=-c x^{n+p} -b x^n + (a-c)x^p -b$$ where $c>0, \, \, a-c >0, \, \, 0<p<1, \, \, b>0 , n=2,3, \cdots$ Under what conditions this equation has zero solution, one solution, ...
-2
votes
0answers
46 views

solving the heat equation

I'm trying to model the diffusion equation on mathematica, but I'm a complete beginner. So far I've managed to find the heat equation on the NDSovle examples but I'm not really entirely sure what all ...
4
votes
1answer
80 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
75 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
45 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: ...
0
votes
0answers
36 views

Solve provides inter-dependent solutions not only variable dependent solutions

I have four implicit equations and trying to find the rest points of a system by using replicator equations. ...
2
votes
1answer
53 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
55 views

Help inteprete the solution given by reduce

i am trying to solve for the a2 in the below equation on Mathematica ...
1
vote
1answer
84 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
32 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
90 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 ...
0
votes
3answers
62 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
39 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 ...
1
vote
1answer
107 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
332 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
45 views
0
votes
1answer
32 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
61 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 ...
1
vote
1answer
44 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
60 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: ...
6
votes
3answers
174 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: ...
1
vote
2answers
125 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 ...
0
votes
1answer
61 views

How find solve the equation complex conjugate? [closed]

Tried solving it with every function I know but couldn't z*=z^2