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

learn more… | top users | synonyms (5)

1
vote
2answers
75 views

how do I control the output of Reduce function?

Reduce[x*y > 50 && x*y < 100 && x < 100 && x > 1 && y > 1 && y < 50, {x, y}, Integers] what if I want ...
1
vote
1answer
50 views

Expectation of Largest Roots of Bernoulli distributed coefficient Monomials

I am interested in determining the most probable maximum values of the real roots of polynomials of form $P(x)=\sum_{k=0}^n a_{k} x^k$ where the degree $n$ will have a defined value (say 3,4,5...) and ...
0
votes
0answers
32 views

Why Mathematica does not Maximize when using parameter

I have recently started using Mathematica and I have got a question using it. I would appreciate if one could help me figuring out how to handle it. I have the following simple maximisation code <...
1
vote
1answer
67 views

How can I solve my system of simultaneous polynomial equations?

I want to solve the system of equations (y + 1)(a - x^p*y^q) == 0 (y + 1)x^p*y^q - c*y == 0 But I am getting the massage this system can't be solved by ...
7
votes
1answer
126 views
1
vote
1answer
46 views

solve equation with integer maximum [on hold]

how to solve with Mathematica a)$ \left [\kern-0.10em\left[ 5 x \right]\kern-0.15em\right] = 2x+1$ b) $ \left [\kern-0.10em\left[1/ 5 x \right]\kern-0.15em\right] > 2x+1$ EDIT = double ...
3
votes
2answers
86 views

solving PDE equation like Helmholtz equation in 2D

In my project I need to solve following equation analytically could anyone help me ? As I read the other questions, my equation seems like Helmholtz equation $$ \triangledown^2 u(x,y) - k_cu(x,...
2
votes
5answers
161 views

Intersection coordinates of two spheres

I am trying to obtain a list of coordinates at which two spheres intersect. Take for example the spheres: sp1=Sphere[{0, 0, 0}, 1] and ...
0
votes
0answers
40 views

Solving linear system with non-commuting coeffcients

Is there a way to solve a linear system of equations where the coefficients do not commute? (Warning: my two-days of looking so far suggest this may be an unsolved math problem, but I figured I could ...
1
vote
1answer
41 views

Splitting Logical Expression in list of expressions

I have long results of a Reduce statement in the form of {(expr1) || (expr2) || (expr3) || ...} I am looking for a way to split ...
0
votes
1answer
83 views

Solving a System of Simultaneous Equations [duplicate]

I have the command: Solve[{Cos[η] == Sqrt[3/6], Sin[α] Cos[η] == Sqrt [1/6], Sin[α] Sin[η] == Sqrt [2/6]}, {η, α}] I get the output ...
1
vote
1answer
71 views

getting a following error,large data points,desired output-best fit to expt. data sets

I am trying to carry out list operation but running into a following error I have large data sets(more than 0.2 million data points) and desired output will be a best fit (numerical data points ) to ...
3
votes
1answer
70 views

Generating plane equation from LinearSolve

I will ask a simple question and might have an issue on the site that explains better about it, but not found. I am formulating a code that defines me an equation that I can generate a plot. ...
1
vote
0answers
51 views

NSolve and FindRoot failing to evaluate

So I am integrating a Piecewise function and then using NSolve to find out where the limits of integration lie to satisfy an ...
2
votes
1answer
66 views

Finding input of the function $f(a,b,c) = (d,e)$ such that $|d-e|$ = constant for $d\in[d_0,d_1]$

The actual question contains a few more parameters than mentioned in the title, but the idea will remain very similar. Lets begin abstractly; I have a certain function $f(a,b,c) = (d,e,g,h)$. I am ...
0
votes
1answer
53 views

Find the minimum of several functions

I have 6 functions of four variables $ f_i: \mathbb{R}^4 \rightarrow \mathbb{R},\, i \in 1..6$ For each function $f_j$ I want to find the subset of $ \mathbb{R}^4 $, called $S_j$, for which it is ...
0
votes
0answers
62 views

solving a set of 10 non-linear system of equations

I have a system of equations and I want to solve it to get a1, a2, b1, ...
0
votes
0answers
31 views

Making function that returns output of FindRoot [duplicate]

I'm trying to make a function that returns the solution to an equation which involves three variables, where the input variables for the function are the other two variables. So far, it runs, but ...
4
votes
2answers
246 views

Why Can't `DSolve` Find a Solution for this ODE?

I wanted to find a basis for the set of solutions of the following ODE. $$y^{''}+\frac{1}{x^2+1}y^{'}(x)+\left[-1-\frac{1}{x^2+1}\right]y(x)=0$$ But when I try to use ...
0
votes
2answers
36 views

Solve inside of InputField is not dynamic

On the 7th line, I have an InputField that I want to dynamically change as I change the input. It solves an equation that is later used to determine the change in y intercept in the graph. However, ...
3
votes
2answers
69 views

Using Solve[ ] inside a Module

I want to use Solve[] inside a Module. If I make the variables solved for local to the module, they are treated differently than ...
1
vote
1answer
49 views

Using solution of an equation [duplicate]

I want to solve something like f(x)=0 and then have the real solution be set as the value of another variable. I can't figure out how to do it. I tried something like this as an example, but it didn't ...
5
votes
1answer
263 views

Finding an analytic solution of a cubic equation

I have been trying to solve a cubic equation $$y=zy^3 + z$$ in $y$ – that is, my desired result is a function $y(z)$ satisfying the equation. Now, there are three solutions of this equation and ...
0
votes
0answers
3 views

Is this equation true? [migrated]

As the question states, does this equation hold true? $\sum_{j=0}^n \sum_{E \in {n \choose j}} (-1)^{|E|}(n-|E|)! = \sum_{j=0}^n(-1)^j(n-j)!{n \choose j} $ From what I understand, this holds true at ...
0
votes
0answers
34 views

NSolve on a function with NIntegrate

I have a function defined with an NIntegrate. The function is of x,y,z, integrated across t: ...
1
vote
0answers
97 views

how to solve a high-dimension system faster, please

I want to solve a high-dimension system as below. If the size is 50, there are 50^2 equations and find the root cost about 6s in my PC. If the size is 100, about 100s. But if size is 500, the time is ...
0
votes
1answer
43 views

Solving a system of integral equations

Is it possible to solve a system of integral equations in Mathematica? More specifically, I would like to obtain numerical solutions for $\mu$ and $\sigma$ from the following system: ...
0
votes
0answers
32 views

Solve a simple equation for a unknown indexed by a real number

I have the following equation. ...
0
votes
2answers
45 views

Find a solution to a set of equations, within a specified range

Given the following list myList = {a + 2 g, -2 c d - 3 b f + 2 a g, d^2 f - c d g, -2 c^2 - a f, c d f - c^2 g} of five expressions in the variables ...
4
votes
2answers
143 views

Solution of a System of Equations Using `Solve`

Part 1 I am trying to solve a simple system of equations as follows Solve[{A x^B == f, A y^B == g}, {A, B}] But I just get the error Solve::nsmet: This ...
6
votes
3answers
207 views

Approximate analytic solution to a polynomial equation

The analytic solution of the equation $$ 1-\frac{2M}{r}+\frac{Q^2}{r^2}-\frac{\Lambda}{3}r^2 = 0 $$ obtained by using the code ...
1
vote
1answer
58 views

Proper way to create plot of equation with parameter solutions

for example I am trying to execute this code: ...
2
votes
0answers
87 views

How to define amazing Goodstein's sequence?

There is an amazing and counterintuitive theorem: For all $n$, there exists a $k$ such that the $k$-th term of the Goodstein sequence $G_k(n)=0$. In other words, every Goodstein sequence ...
3
votes
2answers
92 views

Henon Map Fixed Points Plot versus Iterations and Plot of the Map

For the Henon Map: $$ x_{n+1}=y_n+1-αx_n^2, \quad y_{n+1}=β x_n$$ I would like to discover period doubling bifurcations by varying the parameter $α$ and plotting $x_n,y_n$ versus the iterations $n$ of ...
1
vote
1answer
49 views

BSplineFunction defies numerical solution

I am trying to find an intersection between a straight line and a BSpline. The lines: ...
1
vote
3answers
163 views

Solving my graduation exam geometry problems with Mathematica [closed]

How capable is Mathematica when it comes to typical school geometry problems? Is there a way to throw constraints at it and get it to spit out a solution? Here are two geometry problems from my ...
3
votes
2answers
65 views

Finding Real Roots and Determining Range

I am interested in determining the minimum and maximum values of the real roots of polynomials of form $P(x)=\sum_{k=0}^n a_{k} x^k$ where $n$ will have a defined value (say 3,4,5...) and $a_k$ are ...
0
votes
2answers
76 views

Finding and plotting a parametric solution to a complicated equation (transcendental, log-polynomial)

I am trying (desperately) to find a way to solve a transcendental equation whose solution $x$ depends on non-numerical parameters $a$ and $b$. And then to produce a ...
1
vote
2answers
46 views

NSolve and domain specifications

I am using NSolve to find roots to a system of polynomials that describe some chemical reactions. However, I am seeing some odd behavior when I restrict the domain. First, the basic setup: ...
1
vote
1answer
63 views

Helping Solve to solve

I am developing quite an involved bit of code (for me) that is not finding solutions with Solve when it should. The relevant part of the code is ...
3
votes
1answer
121 views

How can I get exact solutions of this system of equations?

I want to solve system of equations \begin{cases} 2 x^2-5 x y-y^2=y \left(\sqrt{x y-2 y^2}+\sqrt{4 y^2-x y}\right),\\ \sqrt{3 y}+\sqrt{x^2+2 x}-x-x \sqrt{2+9 y^2}=0. \end{cases} ...
0
votes
1answer
110 views

Solve returns empty list

I want to solve these equations but Mathematica gives no answer. ...
0
votes
1answer
40 views

finding the coordinates of intersection point of two complicated implicit function [duplicate]

I have two complicated functions and i plot the contours of them like this: ContourPlot[{f[x,y]==0,g[x,y]==0},{x,x1,x2},{y,y1,y2}] I would like to find ...
0
votes
0answers
74 views

Gauss-Jordan program in Mathematica

Hi to everyone I made this program to solve a linear system by Gauss Jordan, this is my code to solve the system: ...
0
votes
1answer
59 views

Nested double sum does not converge

I am quite a beginner, and have the following problem. I have a sum that comes from Poisson distribution and for each index there corresponds a binomial-type sum. I try to find its root for the ...
3
votes
1answer
52 views

Solving biharmonic equation with Mathematica

I would like to solve a biharmonic equation in polar coordinates of the form: $\Delta \Delta \Phi[r,\theta] = r^i cos(j \, \theta) \quad i,j \, \epsilon \, \mathbb{N}_0 $ I know that a solution for ...
0
votes
0answers
46 views

Solving a non-linear equation [duplicate]

I have one non linear equation, and I am trying to get value of x but when i employ Solve function as below ...
0
votes
3answers
78 views

Issue finding roots in a polynomial [closed]

I am trying to find the roots of the polynomial (-2 + x)^3 (-2 + x^2) (-4 + x^3) (4 + 2 x^2 + x^4) (-8 - 8 x - 2 x^2 + x^3 + x^4) . I am using the command ...
2
votes
2answers
282 views

How to solve an equation with a nested function

I have the equation f[f[x]] == 28 + 9 x How can I solve this for f[x]? I note that this post relates to the topic, but ...
2
votes
0answers
67 views

Solving an equation entered by the user via the Input function

I am new to Mathematica. I am trying to create a program that takes in an equation from user input and then gives the answer. I started with a manipulate function as I created a similar program for ...