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

learn more… | top users | synonyms (5)

0
votes
1answer
55 views
2
votes
2answers
70 views

solve system including piecewise function

I've read posts about how to do this in a direct way, but the method doesn't work for my simple system? -- see code: ...
0
votes
1answer
1k views
-1
votes
0answers
30 views

Finding roots to Interpolation function [duplicate]

I am attempting to find the roots (intersection is constant Y-value) of an Interpolation function. I can do this by observing the plot and then entering search start values based on the visual ...
0
votes
2answers
36 views

How to solve equations involving binomial and summation expressions

Mathematica is taking forever to solve the following equation. Is there any other way t solve this equation for x? ...
0
votes
0answers
48 views

Why does NSolve not solve this system of equations on a bounded domain? [duplicate]

I have three functions $E1,E2,E3$ of $t1$ and $t2$. The expressions are slightly complicated and involve trigonometric functions. For clarity purpose, they are given at the end of the question. I wan'...
2
votes
1answer
82 views

Way to simplify an inequality with many variables

my problem is the following: I have three inequalities in five variables $x,u,a,b,c\in \mathbb{R},x>0 $: ...
1
vote
1answer
40 views

Determine parameter from which on there is no more root for a given function

Let $\gamma>0$ be a real number and $\Phi(r)=\frac{1}{r}-\frac{\pi}{4}\left(H_0(r/2)-Y_0(r/2)\right)$ defined on $[0,\infty)$, where $H_0$ is the Struve function of order zero and $Y_0$ is the ...
0
votes
2answers
164 views

Solving Boolean equations

@Artes suggested this code to me to solve this system of equations: ...
0
votes
1answer
64 views

Do not understand the result I'm getting from Solve [closed]

I did Solve[k2 Cos[x] - k1 Sin[x] == 0,x] Since tangent is sin over cos, the solution must be arctan(k2/k1) But ...
1
vote
1answer
48 views

How to solve an iterative integral equation for a function in Mathematica 8.0?

I would like to solve the following iterative integral equation in order to find the functional form of $P_{0}(k)$ numerically and then use it subsequently for the rest of my code: ...
2
votes
1answer
126 views

Undershoot/Overshoot Method for this differential equation?

I have tried to solve this equation for some weeks and I am not capable. I have read in articles that it is easy with an undershoot/overshoot method, but I don't know how to do it. $y''+\frac{3}{x}y'-...
1
vote
0answers
42 views

diophantine linear equation with condition on the sum of coefficients

I am trying to solve the following diophantine equation x*a + y*b == c where a,b,c are integers and the absolute value of their sums is, for instance, 4. Then I ...
0
votes
1answer
30 views

FindRoot outputs a lot of nlum and ReplaceAll errors before outputting (close) root

I'm trying to find the root of the root function when some other variable is subtracted. I.e. FindRoot[root[theta, r, h]-H, theta] Whenever I do this, FindRoot ...
0
votes
1answer
43 views

Evaluating Root forms in a Table [closed]

When I put a Root form in table, the parameters of the Root form don't evaluate. I don't know how I can indexed values substituted into root form in the table to get have numeric output. ...
1
vote
2answers
135 views

Solving system of equations with (nested) Bessel Functions

I'm trying to find solutions to a system of equations which include Bessel functions. It feels like the problem for mathematica is that the arguments of the Bessel functions are functions themselves ...
1
vote
1answer
68 views

Nonlinear Markov chain (numerical simulation)

Suppose you have a linear Markov process, and you can write it as x(t+1) = Ax(t). Here x is the vector of values, and A is the transition matrix. Since this is linear, it can be solved analytically, ...
0
votes
1answer
52 views

Solving and Plotting Infinite sums over solutions to transcendental equation involving Bessel functions

I am trying to use Mathematica to plot the following equation $E(q,\Delta)$ vs $qa$, for set values of $ D \Delta/a^2$ and $\bar\rho a/D$. I have looked at other stackexchange posts which deal with ...
1
vote
0answers
76 views

Solve equations with Monte Carlo

I am dealing with a complicated problem. I will use a simple problem to explain it. I have two variables x and y, and two equations: x+y=A 2x+y=B The value of A and B is determined by measurement, ...
0
votes
1answer
67 views

Stopping NDSolve when encountering stiffness

I am solving a differential equation for different initial conditions using ParametricNDSolveValue. I need to look at the value of the solution at some later point, ...
-1
votes
1answer
112 views

Solve an equation in several variables

I'm new to Mathematica, so my question may be quite trivial, but I need help. Let $F(x,y,a,b,c,d):\mathbb{R}^6\rightarrow \mathbb{R}$ be a function in 6 variables. I need to find conditions for $x$ ...
0
votes
1answer
32 views

Probems using 2 For and a AppendTo to cycle through my Equation to solve some matrixes

I am trying to solve a few problems here. I have an equation with multiple variables that I am trying to solve in For loop method. I will attach the file below. In addition I am trying to get it to ...
0
votes
1answer
20 views

build absolute value equations know solution [closed]

We have absolute value equations with unknown coefficients: |x + a| = b and we know solutions: x = 11 and x = 5 We need ...
2
votes
1answer
51 views

Finding an Integer, Unimodular Matrix that connects two given matrices

I have two symmetric, integer matrices, $K$ and $K_2$ which have the same determinant and the same signature (number of positive - number of negative eigenvalues). I want to find an integer valued ...
0
votes
1answer
57 views

Solution of Coupled second-order ODEs and plot the diagram

We have two second-order Coupled differential equations as the followings: $$\left\{\begin{array}{lr} \displaystyle \frac{{{d^2}{y_1}}}{{d{x^2}}} = \{ \frac{{\sqrt {\frac{{1 - {\varepsilon ^2}}}{{{{(...
0
votes
0answers
52 views

The ` in Solve results [duplicate]

I assign the result of a Solve to the variable eq8. Then I attempt to use this result in the definition of a function as follows: ...
1
vote
2answers
82 views

FindRoot with Grad

I want to find a numeric solution using Grad. With Solve, I get ...
3
votes
1answer
225 views

Is there a package to find ALL exact roots of a polynomial, if they exist?

There are polynomials with roots not expressible with radicals but expressible as trigonometric or other functions, for which Solve[] only returns ...
1
vote
1answer
44 views

REAL Roots of a 2 variable Polynomial

I am looking to plot the real zeros of polynomials of two variables in Mathematica, but I have encountered an issue. To accomplish this task I have been using ContourPlot to plot the polynonial f(x,y)=...
0
votes
1answer
61 views

Solve homogeneous system [closed]

Let x^2*y + x^2*z + x*y^2 + y^2*z + xz^2 + yz^2+ xyz =0 x^3-xyz + x^2*y-xyz + x^2*z-xyz + xy^2-xyz - xy*z+y^2*z - xyz+xz^2 - xyz+yz^2 =0 x^3+3*xyz+7*yz^2 + xy*z+y^3+9*y*z^2 + x^2*y+6*xyz+4*y*z^2 ...
0
votes
1answer
55 views

Solving for Polynomial roots

This simple Solve gives the roots of a quadratic: Solve[a x^2 + b x + c == 0, x] However, if I factor the polynomial in terms ...
33
votes
8answers
7k views

About multi-root search in Mathematica for transcendental equations

I have some questions for multiroot search for transcendental equations. Is there any clever solution to find all the roots for a transcendental equation in a specific range? Perhaps ...
0
votes
0answers
54 views

Equation cannot be solved with the methods available to Solve [duplicate]

I am a beginner to Mathematica. I am trying to get the solution of such equation as: Solve[-b*M + L*R - a*M*Log10[L*c + (L*d*(1 - M)*S)/R] == 0, R] Constants are ...
0
votes
0answers
38 views

Create a loop for assignment of Solve output [duplicate]

Is there a way to automatically assign the output of solve to a number of symbols? For example, assume that I have the solve statement as follows: ...
2
votes
2answers
49 views

Difficulty finding roots of an interpolation function from NDSolve

I have been trying to find the point at which one of the solutions of a system of two ODEs crosses zero. I used the method suggested in this answer to a previous question, which seemed to be the most ...
4
votes
1answer
85 views

Trying to create an interactive plot (newbie here)

I'm new at Mathematica so please bear with me. I am trying to create an interactive plot that will end up looking like this: I want to input values for certain variables and then plot a curve. This ...
-1
votes
1answer
155 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
2answers
58 views

Using result of Solve as plot parameter [closed]

Recently I have faced a problem I would appreciate it, if you helped me I have the following code in Mathematica I want to plot a function let say z * 10 * t where <...
1
vote
1answer
43 views

How to define a Reduce function in order to define two parameters afterwards

I'm trying to evaluate numerically an equilibrium for a system of ODEs: dA = c A + b B - a A dB = d B + a A - b B So I define a list of known parameters: ...
3
votes
1answer
62 views

Solve with Reals gives different answer

I'm very new to Mathematica (started using ver 10.4) and I was just verifying my calculations. I have the following equation: ...
0
votes
1answer
70 views

Solution for Imaginary part of equation

I have a function Il12i[-0.001, -0.001, w, 0, 1, 0, 0.1002] which is depends on 1 variable w and it is real if w > -3666 (this number I found from graphs). This function is very complicated numerical ...
1
vote
1answer
58 views

Testing equivalence of analytical expressions like $x^2 -x == x(x-1)$

On occasion I have two expressions that I may be equal but simplified differently, and I want to check if they are actually equivalent. Using the equation in the title, $x^2 -x == x(x-1)$, sometimes ...
0
votes
1answer
529 views

Problem with FindRoot applied to functions

I am having difficulty with the error "is not a list of numbers with dimensions..." when using FindRoot (and other numerical routines in Mathematica) to solve equations numerically when the argument ...
0
votes
2answers
47 views

Solving several inequalities in Mathematica

I am a very beginner of Mathematica and the following will probably be a very stupid question. I have a bunch of inequalities in 6 unknowns and I want to find the set of values satisfying them. Can I ...
0
votes
2answers
75 views

FindInstance is very slow on an apparently simple problem

I wish to use FindInstance to find a set of solutions of this problem: ...
4
votes
2answers
835 views

Solving a linear equation in Mathematica

This should be easy but I can't seem to find the right way to do it. I have an equation of the form $a x + b x + c y + a z + d z = 0$, and I'd like to solve for relations between the parameters $a,b,...
6
votes
2answers
269 views

Find a condition that b must satisfy so that Ax=b has solution

I'm new to Mathematica, so I'm sorry if this is really simple. I am trying to find the condition that vector b must satisfy so that Ax=b has solution. I would like to learn a general method, but I'll ...