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
90 views

Solving a system of non-linear equations?

I want to solve the following system of equations: ...
0
votes
0answers
54 views

How can I make an amateur demonstration to solve absolute value equations and inequalities?

I would like to make a program which can solve absolute value equations and inequalities, but I'm a beginner of using the mathematica. I found amazing good demonstrations at the web-page of ...
3
votes
1answer
92 views

Unable to solve equation for a variable by any method

I am looking to solve for the value of r when the derivative of the expression ...
0
votes
0answers
37 views
0
votes
0answers
97 views

Solving Lagrangian (4 vars to solve for)

I'm a bit new to Mathematica, but here's what I've got: ...
1
vote
1answer
83 views

Solving trigonometric functions in Mathematica

I am new to Mathematica language and recently I had the need to solve the following equations with two variables, A and B: ...
2
votes
2answers
2k views

How could I define a function as the solution of equations in Mathematica?

I have posed a specific question yesterday but it may be too trivial to answer. I think the question could be asked in a more general way so it is easier to answer. Then I could solve the original ...
0
votes
2answers
102 views

Finding all complex polynomial roots in a specified range efficiently

I need to find the roots of a rational polynomial that are near i. In the following code, I try that two different ways. First, I use a constraint to only find roots in the right region. Second, I ...
0
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1answer
71 views

Integrate over FindRoot solutions

I have a function of bivariate normal PDF and its marginals defined as ...
0
votes
1answer
44 views

Using the Solve function [closed]

I am new to using Mathematica and am attempting to find the roots of a function using the Solve[] function. I can replace $f[x]$ within Solve[] with the actual function and it will work that way, but ...
1
vote
1answer
73 views

System of nonlinear equations

I am new at mathematica, and I am trying to solve the following system of four equations (f11==0 ,f12==0 , f13==0 , f14==0) under mathematica 10 , they depend on the real variables "alpha, beta, R and ...
5
votes
1answer
198 views

Finding and plotting roots with parameter

I have the following function: $$u(x,t)=\sum_{k=1}^\infty\frac{v_0 L}{\lambda_k c \sin\left(\lambda_k\right)}\sin\left(\frac{\lambda_kx}{L}\right)\sin\left(\frac{\lambda_kct}{L}\right)$$ and this ...
1
vote
0answers
39 views

solving with numerical methods [closed]

Hi I would like to solve the equation below in Mathematica.Since I am a beginner I can not solve it with NSolve and Solve.I don't know why.Do you have any idea?! ...
2
votes
3answers
437 views

Solving an equation involving an integral

How do I get the following into Mathematica, solving for $a$: $$ 0.7 = 1 - \frac{2}{a} \times \left[ \frac{1}{a} \int_0^a \frac{x}{\exp(x)-1}\mathrm dx + \frac{a}{6} - 1\right] $$
4
votes
0answers
104 views

Why does Solve work in v9.0.1 but not in v10.3.1

I want to solve the following DE $$ P'=k(M-P)P, P[0]=53.08, P[50]=23.192, P[100]=76.212.$$ The Mathematica command is ...
4
votes
0answers
70 views

Improve Accuracy of FindRoot

This is a follow up question to an earlier questions I asked. The link is: Product of $N\ 2 \times 2$ matrices and subsequently solving an equation dependent on the product As I am new here, I am not ...
1
vote
0answers
43 views

How can I use x->Root outputs from Solve? [duplicate]

Do not understand the meaning of the output given by Mathematica to this equation: ...
1
vote
3answers
82 views

How to use Solve command? [closed]

I have written a code like follows: ...
0
votes
1answer
123 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 ...
21
votes
1answer
280 views

Fast calculation of discrete logarithms

Does Mathematica have any built-in fast algorithms for calculating discrete logarithms over $(\mathbb{Z}_p)^\times$ (the group of integers modulo $p$)? Essentially, for a fixed large prime ...
5
votes
0answers
143 views
0
votes
0answers
133 views

Why is Mathematica not solving this equation?

Every time I am trying to solve this equation Mathematica is just not doing anything. First time is showed error as quantity is not quantified or something. But since then whenever I am trying to ...
0
votes
0answers
63 views
1
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0answers
35 views

complex algebra with Solve function [closed]

I wanted to solve this complex expression for L, Solve[(1/(R + (1/Iwc)) + (1/(R + IwL)))^-1 == R, L] where I is sqrt(-1) and mathematica is out putting {}. Does ...
1
vote
1answer
51 views

Getting the conditions for equation to be solvable

I have a parametric equation to be solved, but I do not actually care for the solution. I only want to know the range of parameters for which the equation has a solution. Is there a way to get the ...
1
vote
1answer
78 views

Having issue for solving a system with seven equations

I have a system with seven equations and three constrains. I tried to solve them using NSolve, but it takes forever without getting any result. Also, I tried it ...
1
vote
1answer
80 views

DSolve - Complex Number Solutions

some of you know that I have been working on my dissertation of Game-Theoretic Modelling of Cybersecurity (Thank you again to everyone who has helped me with Mathematica so far). The differential ...
0
votes
0answers
91 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 ...
1
vote
2answers
88 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
47 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 ...
2
votes
1answer
120 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
2answers
434 views

Solving an equation takes too long

I am trying to solve the following equation func[a, b, c, d, e] == 0 where ...
20
votes
2answers
5k views

Can Reduce *really* not solve for x here?

Sometimes I get the feeling I'm just flailing blindly with Mathematica. Is solving for $x$ in the equation $$ \frac{\cosh (x/2)}{x} = \sqrt{2} $$ really beyond the scope of Mathematica? I try to ...
20
votes
2answers
4k views

How do I work with Root objects?

I want to solve the trigonometric equation : $$(3-\cos 4x )\cdot (\sin x - \cos x ) = 2.$$ I tried Solve[(3 - Cos[4*x])*(Sin[x] - Cos[x]) == 2, x] It returns the ...
1
vote
1answer
69 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
1answer
88 views

How to equate coefficient of two polynomials? [closed]

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
9
votes
3answers
490 views

Using NSolve in the complex plane

I am trying to find numerical values for $\Im\ e^{\frac{1}{2} +i\ y} = \Im\ \zeta(\frac{1}{2} +i\ y)$ for a given range. I have tried: ...
0
votes
0answers
59 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
0answers
84 views
0
votes
1answer
52 views

Multiple stopping constraints in NDSolve

I need to numerically solve several differential equations, with several constraints, like this : ...
1
vote
1answer
160 views

Why does Mathematica not restrict the domains of Rational Expressions?

As taught in High School Mathematics: $$\begin{array}{ccl} \left\{ {(x-3)(x+3)\over 5(x+3)} : \ x\ne -3 \right\} & \ne & \left\{ {x-3\over 5} : \ x\in\mathbb{R} \right\} \\ \left\{ ...
0
votes
1answer
88 views

How to solve the following GR PDE?

Someone could help me for solving the following GR PDE? (this code do not work yet) ...
3
votes
0answers
73 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]: ...
0
votes
1answer
52 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 ...
2
votes
1answer
70 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
71 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
52 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
65 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
66 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] -> ...