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
21 views

NDSolve::ivar error when trying to solve DE [on hold]

I am getting this error: NSolve::ivar: 0 is not a valid variable, when attempting to solve the following problem. ...
1
vote
2answers
60 views

Closed form solution equations involving finite sums

I am a beginner in Mathematica, so take this into account. I could not find anything similar in the internet so far. I am trying to find a closed form solution for ...
2
votes
1answer
36 views

FindInstance skips solutions

I have an equation to compute the bit-error rate of a binary symmetric channel: $$P_{err}(n,p) = \sum_{k = \frac{n-1}{2} + 1}^n\binom n k p^k(1-p)^{n-k}$$ I then want to find the smallest ...
0
votes
0answers
67 views

Solving general system of equations

I want to find the closed form solution to a general system of equations. The number of equations and variables is C. How do I specify the system of equations? If ...
0
votes
1answer
81 views

Help on using Solve

I tried to use Solve to solve a set of nonlinear equations and got this error: Solve was unable to solve the system with inexact coefficients or the system ...
1
vote
1answer
60 views

Double arrow in the outcome

Does anyone know how do I get rid of one of the double part at the start of the outcome rh-> rh-> ...
-4
votes
0answers
44 views

How to solve this equation? Which command should be applied? [on hold]

I am trying to find T1 from attached equation, but it can not solved by "solve" in mathematica. how could i solve this equation?
4
votes
1answer
73 views

How to equate coefficient of two polynomials? [on hold]

Given two polynomials, How can I equate coefficients of them in Mathematica? For instance a + b x + (c+d) x^2 + (e+f)x^3 == 0
1
vote
1answer
97 views

How to handle a special Neumann-like boundary condition in NDSolve?

How to solve the following nonlinear ODE with two algebraic equations and one boundary condition? ...
0
votes
0answers
55 views

Is this problem parametrically solvable or it can just be solved for specific $\sigma$ and $\theta$?

In order to solve This problem: What is the maximum value of coefficient fv with the constraint that the matrix is positive semi-definite?, I have used the following code (Determinant is computed by ...
0
votes
1answer
48 views

Multiple stopping constraints in NDSolve

I need to numerically solve several differential equations, with several constraints, like this : ...
0
votes
1answer
76 views

How to solve the following GR PDE?

Someone could help me for solving the following GR PDE? (this code do not work yet) ...
0
votes
1answer
48 views

Using Solve with Mod [closed]

I'm new to Mathematica, and it seems like what I'm doing should be a simple operation, but I can't seem to get it to work, or return the right result. I'm assuming I'm doing something fundamentally ...
3
votes
0answers
63 views

Low accuracy while solving a multi-variable equation numerically

My question is as following: I was trying to make a function Vs2[r] with two parameters fit a set of conditions. Vs2[r]: ...
2
votes
1answer
64 views

How to get the analytical solution of this equation set

There is a equation set: {2 x^2 + 49 - 7 x - 2 x Sqrt[x^2 + 49 - 7 x] Cos[rad] == (7 - x)^2, 2 x^2 + 49 - 7 x - 2 x Sqrt[x^2 + 49 - 7 x] Cos[rad + Pi/3] == 49} ...
0
votes
1answer
65 views

what do those signs #1, #1^2, #1^3, & mean here? [duplicate]

I have read common pitfalls page and the documentation page but I still don't understand what do those signs mean here? ...
0
votes
1answer
45 views

How to represent one variable in terms of others in a system of equations? [closed]

I have an pretty complex equation set But when I clicked Ctrl+Enter (a.k.a Evaluate Cell), nothing happened. What should I do?
3
votes
1answer
52 views

Havin the problem with solving a nonlinear overdetermined system of equations

I am having a problem to solve a nonlinear overdetermined system of equations. According to one of the previous posts, I tried NMinimize, but it didn’t work. Shall ...
0
votes
1answer
45 views

Need Help with solve function [closed]

I'm trying to re-write this function x = e^(-(r+(1/2)*sigma^2)*t-(g)(sigma)*sqrt(t)), as an expression of "g" instead of "x" ...
0
votes
0answers
79 views

FindInstance—why doesn't it work with my expression?

I want to find arbitrary solution of a system of equations: ...
0
votes
1answer
63 views

Computing quadrature points on triangle

According to http://math2.uncc.edu/~shaodeng/TEACHING/math5172/Lectures/Lect_15.PDF page 7, it is possible to compute coordinate of quadrature points by using the script ...
0
votes
0answers
19 views

Solving a simple ODE [duplicate]

I am trying to solve $y(x)' = \sqrt{y(x)}$ with initial condition $y(0)=0$ for $x\in \mathbb{R}$. I have tried this: DSolve[{y'[x] == Sqrt[y[x]], y[0] == 0}, y[x], x] but this gives {{y[x] -> ...
0
votes
0answers
50 views

Riemann Zeta function definition was expanded by Euler with an infinite product series [duplicate]

The Euler infinite product series definition for Riemann's zeta function requires that Mathematica use all prime numbers in the product series. Can anyone help me with the code that will give a ...
1
vote
0answers
77 views

Using functions in Solve [closed]

i wanted to calculate the real roots of a function. To my knowledge the function i defined has no real roots, so i expected an emptyset, but instead i got some Root[...#..] answers by Mathematica. ...
0
votes
1answer
52 views

$4$-d system of second order PDEs

I have a $4$-dimensional nonlinear system of second order PDEs with periodic boundary conditions. Let $y(t,x)=(y_1(t,x),...,y_4(t,x))$ with $t \in \mathbb{R}$ and $x \in [0,1]$ then the system is ...
3
votes
0answers
129 views

Strange behaviour of NotElement in Reduce

I have observed curious behaviour on domains supplied to NotElement and Reduce and domain of an argument in calculation inside ...
2
votes
1answer
93 views

Issue with NSolve for solving six equation and six unkown [closed]

I am trying to solve the following six equations and six unknown but It takes me one hour then the program stops. Would you please give some help. I am a beginner. $eqe1=0.000466667 \left(A_2 \cosh ...
2
votes
1answer
58 views

How to plot linear term of a function expanded by Taylor seires in Mathematica?

I am quite new in Mathematica and I am trying to plot a linear term of a particular function in Mathematica. I have tried something like this: ...
0
votes
1answer
44 views

Simple grouping equations [closed]

I'm new in the Mathematica world. A very basic question. I have been using the command Eliminate on a set of equations as follow: ...
0
votes
0answers
31 views

Using Solve with NIntegrate [duplicate]

I have a function defined as a numerical integral of a parameter. When I try to solve for the parameter Mathematica complains that the integrand has evaluated to a non-numerical value (which makes ...
0
votes
1answer
71 views

How can I calculate the root of any order of power series

How can I calculate the root of any order of power series with Mathematica. Here I insert every quantity by hand. But I want to give a, ...
0
votes
1answer
55 views

Eliminate variable on multiple equations [closed]

I'm pretty new with Mathematica. I have to perform a really simple operation, but I'm really struggling with that. I have a set of 4 equations, for example (they can also be more complex): $ AA = 2 ...
0
votes
3answers
59 views

How to find the value of a variable using solution of Simultaneous equations? [closed]

I have to find the value of p where p=a1*x+b2*y; using the solution of the equation ...
0
votes
1answer
163 views

How can I solve a 3D heat transfer partial differential equation? [closed]

It's a problem about heat transfer. Here is the equation : Is it solvable using this software? Edit Sorry, I'm new to Mathematica. I have the following code for this problem ...
2
votes
1answer
86 views

How do I find the analytical roots of this polynomial? [closed]

I want to find the analytical roots of this polynomial - x - a^3*x*(a^2*x*(a*x*(x - 1) + 1)*(x - 1) + 1)*(a*x*(x - 1) + 1)*(x - 1) ...
-2
votes
0answers
29 views
0
votes
0answers
73 views

Errro in plotting the results of FindRoot [closed]

I would like to plot the results of FindRoot over certain range of one input. First of all I am sorry that the equation is a bit long and messy. I have tried to ...
0
votes
1answer
37 views

Transform system of equations while leaving solution set invariant?

Consider the example system of equations syst==res where syst={x + 2 y + 3 x y, 1 + 4 x + y}; res={0 , 0}; Solving for the ...
1
vote
0answers
43 views

Solve Two Functions In Three Variables and use ContourPlot [closed]

I am solving this system in mathematica ...
0
votes
1answer
36 views

Simplify doesn't simplify multiple conditions from Reduce

Consider the following simple example where I try to solve an equation and then apply a bounded interval to find the right result out of an infinite amount of solutions: ...
2
votes
1answer
62 views

FindRoot of interpolating function from NDSolve

I am having issues finding the root of an interpolating function obtained from NDSolve. For example: ...
0
votes
2answers
61 views

Graph plotted in W|A but not Mathematica

This Mathematica code gives me a blank graph but if I run it on W|A I get a result. Why? ...
2
votes
3answers
207 views

Simultaneous equations—classify the solution set as finite, infinite, or none [duplicate]

How do I find the values of $b$ and $c$ for the equations $x + 5 y = 4$ and $2 x + by = c$ with a unique solution, an infinite set of solutions and no solutions with Mathematica?
1
vote
1answer
49 views

Solving a simple trigonometric equation in a range

I would like to solve a simple trigonometric equation, for example $\sin\theta=\frac{1}{2},$ but Solve gives the single solution obtained by using the inverse ...
1
vote
1answer
64 views

How do I plot this (x^3 - 2*x)^Ln[x]? [closed]

y=(x^3 - 2*x)^Ln[x] I'm totally clueless. I tried with y=e^(Ln[x] Ln[-2 x + x^3]) by Ln-ing on both sides but there is ...
1
vote
0answers
44 views

Strange behavior when solving absolute value equations

Try this: Solve[Abs[x/2 - 1/3] == 1, x] Produces this answer: (* {{x -> -(4/3)}, {x -> 8/3}} *) Now try this: ...
0
votes
0answers
60 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 ...
12
votes
3answers
366 views

Is there any predictor-corrector method in Mathematica for solving nonlinear system of algebraic equations?

The FindRoot Function in Matheatica can easily be used to solve systems of nonlinear algebraic equations. But, I want to solve a system of nonlinear equations with variations of some parameters. ...
0
votes
0answers
41 views

Solving non linear equation system

I need to solve 4 non linear equation systems I tried with 1 system, but it keeps telling me "498" +(t^3)*(y^2))/((12.6*10^11-ty-tx)^2)-(42*t)/(12.6*10^11-t*x))= 0},{x,y}] " is incomplete; more ...