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

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1
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1answer
47 views

Maclaurin Series - Table

I'm starting to learn Mathematica. I have to solved this eq and draw the graph. It is developing a series of Taylor in about x0 == 0. This is my equation to solve ...
0
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1answer
80 views

Maclaurin series [closed]

Can someone tells me, why is that not working? I'm starting to learn Mathematica. I have to solved this eq and draw the graph. It is developing a series of Taylor in about x0 = 0. ...
1
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0answers
56 views

Obtaining values from interpolating functions

A similar question has been asked in the post HERE but the current question is more complicated: I have the following differential system ...
-1
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2answers
91 views

linear system equation ( trying to solve ) [closed]

I am trying to solve this system 3.7 x1+51.5 x10+71.3 x11-84. x2-16. x3-57.7 x4+89.7 x5-54.9 x6-85.8 x7+57.8 x8-51.3 x9==-36.8 -86.3 x1+5.7 x10-0.2 x11-39.9 x2+52.6 x3-45.6 x4+78. x5+90.7 x6-86.2 ...
0
votes
1answer
52 views

Reduce in NDSolve [duplicate]

Second order ode; neither the trig RHS simplifies nor is the solution obtained readily: ...
1
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0answers
49 views

How to use interpolating functions in NSolve with a piecewise function?

I have a system of two non-linear differential equations that are piecewise, the solutions of which I would like to use to obtain the values of a third variable that is also piecewise. I have trouble ...
1
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0answers
82 views

Interpreting Root Objects [closed]

I have solved this system of equations in Mathematica for $x$ where the coefficients of the equations were functions of $a,b$ and $c$. Mathematica then displays real solutions $x$ with constraints on ...
1
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1answer
33 views

One system consisting of multiple linear equations [closed]

Hello everyone i apologize if this has been answered before i honestly couldnt find it. The problem im having is that im trying to Define one system with multiple equations something like this: ...
5
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4answers
101 views

Using roots to get original equation

I have a list of four rules, that I would like to use to find the original polynomial that produced them. The rules are of the form ...
3
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3answers
247 views

Why does FindInstance fail when Solve succeeds on these simple constraints?

Why does FindInstance[{a, b} > 0.27 && a == 10^8 && b == 2, {a, b}] fail even though ...
2
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2answers
90 views

How to find the integrand singularity points when having NIntegrate::slwcon:

In order to calculate the closed area of the curve below defined by parametric equation curve02, ...
0
votes
1answer
47 views

Extract solutions of linear system to variables

I need to output the answers from solve into the variables named just as they were named in the solve equations. I have checked out this thread Assign the results from a Solve to variable(s) but ...
7
votes
4answers
470 views

How to find a tangent line with 2 points of tangency for a curve?

Say I have a function like this: f[x_] := 4 x^4 - 9 x^3 - x^2 + 10; Plot[f[x], {x, -1, 2}] It's obvious that there's a tangent line with 2 points of tangency ...
1
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0answers
55 views

Artifacts in the solutions of NSolve [closed]

I have (what I think are) some problems with the precision of NSolve. I'm trying to solve this cubic equation: $a f^3(x)-b f^2(x)-c f(x)-z=0$ for the function $f(x)$ and then plot the following ...
0
votes
0answers
28 views

Finding parameters that give constrained eigenvalues of matrix

I want to obtain the eigenvalues $x_1,x_2,x_3$ of a hermitian, off-diagonal matrix, {{0, Conjugate[d], Conjugate[g]}, {d, 0, Conjugate[h]}, {g, h, 0}}, under the ...
2
votes
0answers
29 views

Solving for coefficients of a polynomial? [closed]

I'm sure I'm doing something wrong here, but I'm damned if I can figure out what. I'm trying to find a cubic function that passes through (0, 270), (1, 312), (2,230), (3,0), but the first way I tried ...
0
votes
0answers
46 views

Output of NDSolve is useless when the system gets bigger

I have a bridge, which I want to discretize on $n$ stiff rods. To find a solution I wrote the following code in mathematica: ...
0
votes
1answer
70 views

How to solve a system of integral equations [closed]

I am trying to solve a system of equations as follows... f1[t]/3 == (1/3)[Integrate[f3[t], t]] f1[t]/(6/5) == Integrate[f2[t], t] f3[t] == Integrate[f1[t], t] I ...
0
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1answer
52 views

Solving a System of Equations syntax confusion

I have a system of two equations which I would like to solve in terms of a third unknown variable $s$. ...
0
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0answers
36 views

Find Roots of expression with modified Bessel functions [duplicate]

I would like to solve an equation of this type $$A-B\,K_0(\kappa\,r)-C\,K_1(\kappa\,r)=0\ \ \quad \text{with}\ A,\,B,\,C,\,\kappa\in\mathbb{R},\ \text{known}$$ for $r$. I am not aware whether this ...
1
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0answers
33 views

Rearrange generic expression into a quartic polynomial

I'm rather new to mathematica. I'm attempting to express: $$\sqrt{x} = \frac{\gamma \sqrt{y}}{-i(\Delta - g \sqrt{1 - (\frac{\tau}{4lhx})^2})+\frac{\gamma}{2}}$$ as $$0 = Ax^4 + Bx^3 + Cx^2 + Dx + ...
5
votes
1answer
81 views

Passing starting values to FindRoot when called by the Shooting Method of NDSolve

According to the documentation of the NDSolve Method -> "Shooting" option, it is possible to pass to ...
0
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0answers
65 views

How to systematically approach when solving a large system of differential equations?

I defined several functions in order to get to the final system of a partial differential equations I have to solve. Here is how I did those definitions: ...
0
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1answer
34 views

“Solve” with problem “Solve::ivar: ”-1+t is not a valid variable.“”

Solve[{Ee1*ek1 + g*h*(1 + r) + j1*h*ek2 == ek1, Ee2*ek2 + j1*h*ek1 + j2*h*ek3 == ek2, Ee3*ek3 + j2*h*ek2 == ek3}, {r}] want to get ...
1
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0answers
48 views

Solving a system of equations and inequalities over the reals

I have to solve the following system: $$\begin{cases} 16x^4-40ax^3+(15a^2+24b)x^2- 18abx+3b^2 = 0 \\ 5ax-4x^2-b>0 \\ 15ax-20x^2-3b<0 \\ 4x^3-8 c x^2+5acx-cb <0\end{cases},$$ where $c<0$, ...
2
votes
0answers
65 views

How do I invert a function with two arguments? [closed]

I begin with a function defined by c[u_, mH_] I won't go into details because it comes from countless lines of partial differential equations, boundary ...
1
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2answers
56 views

Solve equation with Log[s]

When i try to solve the following equation, i get error message that "Solve::dinv: ...."due to the presence of Log[s0] term. How to solve this? the code is given below: ...
1
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0answers
31 views

FindRoot::nlnum & Interpolatingfunction

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
1answer
84 views

System of differential algebraic equations with one of the variables as an argument of the other varaibles

This is my first question here and I don't even know what to search for to find a solution. So I'd appreciate it even if someone can point me in the right direction. EDIT: My post had many problems, ...
1
vote
1answer
41 views

How to find function existence border

I have a function like this f[x_, a_] = Log[-x - a]*(-x - a) + Sin[a]; this function does exist if x > a because of Log[]. a - parameters. if I plot a few graphs ...
4
votes
1answer
74 views

How many solutions do you get from simultaneous polynomial equations?

I have the following four simultaneous polynomial equations ...
1
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1answer
106 views

Is the output to Solve ordered or are the solutions randomly placed?

I am trying to find the roots of a polynomial of eight degree $$\sin^8\varphi-2\lambda_i^2\sin^6\varphi+(6\lambda_i^2+\lambda_i^4)\sin^4\varphi-(4\lambda_i^2+2\lambda_i^4)\sin^2\varphi+\lambda_i^4=0$$ ...
2
votes
1answer
68 views

How to estimate the running time of a programme on mathematica [closed]

I am solving a system of 6 linear equations containing six unknowns using mathematica. It is taking too much time and still running after 3 hours. can I estimate the approximate running time? Is there ...
2
votes
1answer
86 views

Putting as many expressions as possible equal to zero

Say I have a list of expressions involving many different variables. I would like to see how many of the expressions I can set equal to zero thereby solving for some of the variables in terms of the ...
3
votes
2answers
180 views

the exact real solutions of cubic polynomial?

Such as the equation:$x^3-5 x+1=0$, according to the cubic discriminant we know it has three real solutions. We can also find the exact expressions of them from Mathematical handbook. However, by MMA ...
0
votes
0answers
37 views

Problems solving differential equation with ParametricNDsolve for certain parameters

I'm working on a simulation of a physical problem for a few weeks now and I'm starting to get really frustrated about it. The problem itself is the stationary case of the heat diffusion equation in ...
1
vote
0answers
51 views

Can Mathematica give the solutions to x^n - 1 = 0 in their radical form [duplicate]

If I input: Solve[x^3 - 1 == 0] Mathematica returns: {{x -> 1}, {x -> -(-1)^(1/3)}, {x -> (-1)^(2/3)}} I want to see the roots expressed as radicals for ...
4
votes
2answers
203 views

General solution for a linear ODE set with complicated coefficient

This is the original problem that motivated me to ask this question. I encountered it when trying to reproduce the deduction in this paper. (I'll paste the relevant part below to make this question ...
6
votes
1answer
250 views
2
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1answer
100 views

How to approximate the solution of a system of quartic equations

In an attempt to evaluate the point at which the cycle 2 becomes unstable for the given map: \begin{equation} x_{n+1}=μ-x_n^4=f(x_n), \quad μ \in \mathbb{R} \end{equation} I have so far managed to ...
3
votes
2answers
73 views

Solving system of equations in Mathematica

I am unable to solve this system of equations in Mathematica. Where the third equation takes value (on the right hand side) from 0.00001 to ...
3
votes
1answer
168 views

How to tell Solve[] to satisfy as many constraints as it can?

Is there any way to tell Solve (or something similar) to return values for variables that solved as many constraints as it happened to satisfy? Edit: I had ...
2
votes
1answer
65 views
0
votes
1answer
66 views

Is it possible to stop NSolve when it finds a single root [closed]

I have a system of nonlinear algebraic equations with following property: if $(x_1,x_2,x_3,x_4,x_5,x_6,x_7)$ is a root of the system, so any its permutation is another root as well. My system contains ...
0
votes
6answers
238 views

Roots of a characteristic equation. Can Mathematica solve it?

I have been using Mathematica for a few years, but with basic things. Now I need to find the first 10 roots of the following equation: ...
5
votes
3answers
447 views

Writing Mathematica's Root function output in a academic paper form

I need to write the following (which is the result of a Solve command I ran in Mathematica) in an academic journal paper: ...
0
votes
1answer
74 views

Transforming from implicit Cartesian form to a parametric form [closed]

First equation $((1.2 x)^2 + (1.4 y)^2 - 1)^3 - (1.3 x)^2 y^3 == 0$ I wanna transform it into a parametric equation. I spent a much of a day working on it without success. The equation describes the ...
3
votes
1answer
85 views

Trying to find a temperature profile with a nonlinear 2nd order ODE. NDSolve very sensitive to seemingly arbitrary constant

I am trying to solve this differential equation for a heat transfer problem: \begin{equation} kt\frac{\partial^2 T}{\partial x^2} = \epsilon \sigma T^4, \ \ \ T(0) = T_0, \ \ \ \frac{\partial ...
0
votes
1answer
48 views

Interactive Application using Manipulate for Fibonacci Series

I am working on creating interactive app using Manipulate function on fibonacci series using SeriesCoefficient. I want to plot the fibonacci numbers based on the slider of Manipulate function. I ...