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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0answers
89 views

Help numerically solve this non-linear PDE with singularity

I have trouble finding a numerical solution to the partial differential equation below. It seems to be a singularity in the solution somewhere, so I searched online and found that it is suggested to ...
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 ...
0
votes
1answer
156 views

Given $y$, find the $x$ value of a point on a Bezier curve

I have linear equation of Bezier curve with one control point: f[x_] := (1 – t)^2 x0 + 2 (1 – t) t x1 + t^2 x2; f[y_] := (1 – t)^2 y0 + 2 (1 – t) t y1 + t^2 y2; ...
0
votes
2answers
37 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, ...
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
265 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 ...
3
votes
2answers
173 views

Randomly generate points on a van der Waals surface

I'm looking to randomly place an atom $\mathbf{A}$ onto a van der Waals surface formed by atoms $\mathbf{B}$, such that the distance between the randomly-generated atom $\mathbf{A}$ and the nearest ...
0
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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 ...
1
vote
0answers
98 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 ...
9
votes
3answers
2k views

NDSolve with vectors

I'm stumped. I'm trying to write this using vectors, but the 2nd derivative isn't being expanded like I expected it to be. This is a system of equations for a projectile with quadratic drag and ...
0
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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: ...
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: ...
4
votes
2answers
144 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 ...
0
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0answers
32 views
0
votes
1answer
62 views
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 ...
6
votes
3answers
208 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
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 ...
8
votes
1answer
252 views

Law of Cosines to determine angle change along spiral

The Spiral I'm trying to place circles along the outside of an Archimedean spiral. Shown below: ...
3
votes
2answers
175 views

More issues Integrate, NIntegrate, FindRoot

I'm trying to solve a system of 3 non-linear equations using FindRoot and Integrate. If I start FindRoot[] close to the right answer, it works well but returns a bunch of error messages first. ...
0
votes
2answers
69 views

Selecting the maximum value from the results returned by NSolve

I'm trying to select the maximum value from the answers Mathematica 7.0 is getting from a simple basic NSolve algebric equation : ...
3
votes
2answers
93 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
50 views

BSplineFunction defies numerical solution

I am trying to find an intersection between a straight line and a BSpline. The lines: ...
2
votes
1answer
109 views

Complicated implicit plotting [closed]

I'm quite new to Mathematica and have already spent tons of time on problems of this type, browsing through tutorials and topics here. I'm now coming to conclusion that it cannot be done and am about ...
1
vote
0answers
60 views

Getting FindRoot::nlnum when trying to find root of an Interpolating function [closed]

I want to solve a system of differential equations and find a point where the solutions cross. So four steps: 1. Solve the system of differential equations: ...
2
votes
0answers
66 views

Estimating processing time for commands [closed]

I am trying to evaluate some equations by using Taylor series of expansion (Series[], ExpandAll[], and Normal[] command), and using n equation and n unknown (Solve). Following is not full command (if ...
2
votes
1answer
44 views

Help Compiling Vectors using Iterations

So I have a nice code that runs properly, which I include below but, in my naiveté, I'm having issues iterating my procedure. Simply put, I have a function of two real variables $f(x,y)$ and I want ...
1
vote
3answers
166 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 ...
2
votes
2answers
81 views

Finding zero of nonlinear simultaneous equations [closed]

I'm trying to find the zero of nonlinear simultaneous equations defined in myfun1 and myfun2: ...
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
80 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
votes
1answer
192 views

Can Mathematica solve this integral numerically?

I need to evaluate numerically the following $$\int_0^{\infty}\exp\left(-\pi\lambda\mathbb{E}_H\left(\int_r^\infty\left(1-\exp\left(-sP_{\text{M}}Hr^{-1/\delta}\right)\right){\rm{d}}r\right)\right)2\...
0
votes
1answer
72 views

Solving equations with change of variables is not working?

I want to express it in the form $$\text{expr=}\int_{-\infty}^{\infty}C_1\exp\left(-t^2\right)f(t)dt$$, i.e., the integrand is a bounded smooth function $f(t)$ times $\exp(-t^2)$ and the domain of ...
1
vote
2answers
47 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
123 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
0answers
75 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
41 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
1answer
83 views
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 ...
13
votes
2answers
272 views

Heat convection differential equations from 1952 - Mathematica “fails to converge”

I am trying to solve a fundamental problem in analytical convective heat transfer: laminar free convection flow and heat transfer from a flat plate parallel to the direction of the generating body ...
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 ...
0
votes
1answer
103 views

How to solve this example `x^2=2^x`? [closed]

How to solve this? I don't know, and ask you )) $$ x^2=2^x; $$
2
votes
2answers
56 views

Plotting the results from Solve in a Manipulate expression

I am a self-taught Mathematica user, trying to make some progress. This is my code: ...
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 ...
1
vote
2answers
92 views

Find smallest solution in Solve's solution set

When an equation has multiple solutions, how do you find the first solution? Example: Say we're trying to find the first positive x-intercept of the cosine function: $cos(x)=0 \land x \ge 0$ ...
0
votes
2answers
416 views

Nonlinear matrix equation solving in Mathematica

is it possible to solve below equation in Mathematica? A.X+B.Exp[X]==C A, B are square ...