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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1answer
45 views

Elements inside arrays seem to be strings rather than signed numbers

When I have code like b = Array[Subscript[be, #] &, {3, 1}] b = b /. {Subscript[be, k_] :> Subscript[-be, k] /; k > 1} I am noticing that Mathematica ...
1
vote
0answers
50 views

Problems finding intersection points between line and generic function

I'm trying to find Intersection points between a line, which is given by 2 points, and a generic function (I want it to be able to handle polynomial functions, circles/ovals, lines and all ...
3
votes
1answer
63 views

How can I solve my easy system of equations?

I am new to Mathematica and am afraid this is a silly question. I have this very easy substitution, it has three equations on three unknowns {w1, l1, t1}. I want to ...
2
votes
2answers
214 views

How to solve this numerically?

May I ask what is the best way to evaluate ...
0
votes
1answer
83 views

In which condition releated to thee coefficients some equation has a solution

Please excuse me if the question seems to commonplace. Can Mathematica give a response to this question: In which condition related to the coefficients $c>0, \, n\geq 2, 0<p<1,\, a>c$ ...
1
vote
4answers
128 views

Solve reports it can't handle my equation

I am trying to solve the following equation Solve[x ϵ + (-ϵ) x^-ϵ - c (-ϵ) x^(-ϵ - 1) == 0, x] Yields Solve::nsmet: This system cannot be solved with the ...
-1
votes
0answers
39 views

Solve inequlities for certain variables. Reduce is not helping [on hold]

Working with few inequalities where two unknowns are there I wanted to find the relation between them. Reduce is unable to give me an answer. What could be done ...
2
votes
0answers
27 views

How to handle solution returned by ParametricNDSolveValue in FindRoot

i was trying to solve a problem relative to root finding in a system of differential equations; here's a simpler case. With two distinct set of parametric differential equations, i'm able to find the ...
1
vote
1answer
58 views

Optimizing matrix inequalities over trace

I need to solve the following problem. Given $n \times n$ Hermitian matrices $A\geq 0$ and $B_1, ~ B_2$ (need not be positive semidefinite), with $Tr(AB_1)<0~,Tr(AB_2)<0$ construct a ...
1
vote
1answer
88 views

4th-order Runge-Kutta method to solve a system of coupled ODEs [duplicate]

I am a beginner at Mathematica programming and with the Runge-Kutta method as well. I'm trying to solve a system of coupled ODEs using a 4th-order Runge-Kutta method for my project work. I have ...
0
votes
1answer
529 views

Solve non linear system of equations

I am trying to solve a system of two equations with two unknowns. In these equations I have, a part from constants: Unknown nr 1, $$D_{\perp}$$ Unknown nr 2, $$\omega_C$$ Known function of r: ...
0
votes
0answers
36 views

Problem in deriving general equation [on hold]

I have a problem to derive a general equation in Mathematica. The code below supposedly computes the intersection area What modifications should I make to the code to derive the area in terms of ...
0
votes
2answers
35 views

Defining the domain of positive real numbers

I am trying to solve an equation by assuming that all the variables are real and strictly positive. I can use the keyword Reals for the argument ...
0
votes
1answer
43 views

FindRoot, Loops and multivariate nonlinear system

I posted a question yesterday asking how I could get all the solutions to my system of 4 nonlinear equations with 4 unknowns. I gave up on this since it seems ...
0
votes
0answers
50 views

If the earth's rotational speed increased by 2% each day starting today…what would be the difference in age 20 years from now? [on hold]

If the new adjusted revolution of the earth still equaled one day and 365 days still equaled one year, how old would someone be 20 years from now (20 years based on the current rotation of the earth) ...
0
votes
1answer
65 views

Eliminating parameter from parametric equation

In Mathematica Online I tried: Eliminate[{x == t + t^3, y == t - t^3, z == 1 + t^4}, {t}] ...
0
votes
0answers
43 views

Any way of solving this system of nonlinear equations with non integer powers?

I have a system of four nonlinear equations. Some of the exponents are fractions. I was wondering if this is what is causing NSolve to run for hours without giving ...
1
vote
0answers
49 views

Why am I getting a conditional output when importing the Dirac Equation to Mathematica? [duplicate]

Just starting out with Mathematica and trying to use the Dirac Equation. I'm working with the following form of the Dirac Equation: $$ i \hbar \gamma^\mu \partial_\mu \psi - m c \psi = 0 $$ And my ...
0
votes
1answer
57 views

Solving a single-variable equation mixed with exponential and algebraic

Trying to solve for x Solve[((a - 1) (1 + d x^2))/(a (Exp[b x + c] - 1)) - e == 0, x] in terms of the constants a,b,c,d, and e. Mathematica says "This ...
14
votes
3answers
2k views

How can I implement the method of Lagrange multipliers to find constrained extrema?

I want to form the function $h=f-\lambda_{1}g_{1}-\lambda_{2}g_{2}$ where $f$ is the function to optimize subject to the constraints $g_{1}=0$ and $g_{2}=0$ so that I can solve the first partial ...
-1
votes
1answer
43 views

Consider function is giving me imaginary numbers and incorrect answer, please help [closed]

Here is the question. Consider the function f(x) = (2-x)/(x+1). -Find all points on the graph of f where the tangent line is perpendicular to the line y=4x. -For each point, report the equation of ...
2
votes
2answers
91 views

Only one root at specific interval

I need a help to find k here: $f(x)=-k^x + x^2$ It is not too simple. I have interest to find the single value of "k" where, inside interval {x,2,3}, the function have only one value to x when f(x) ...
1
vote
2answers
108 views

Solving for the limits of an integral

I am trying to get Mathematica to solve for the symmetric limits of an integral of a Square Wave. ...
-3
votes
2answers
86 views

Solving the symbolic quadratic equation ax2 + bx + c = 0 [closed]

I need to ask Mathematica to solve the symbolic quadratic equation ax2 + bx + c = 0. Does it give you the right answer?
0
votes
2answers
44 views
2
votes
0answers
48 views

Simplify large fractions

Hi i'm quite new with Mathematica and i'm experiencing some problems with Simplify and FullSimplify. I'm dealing with a sistem ...
0
votes
1answer
40 views

NSolve taking too long to solve system of polynomial equations

I am trying to solve a system of polynomial equations (10 variables and 10 equations) using NSolve in an attempt to find all solutions. ...
0
votes
1answer
72 views

How to obtain a convergent solution iteratively for a linear system of equations

I am working on a problem that requires an iterative procedure to solve a linear system of equations, the system of equations in matrix form is: $$\underbrace{\begin{bmatrix} r_{11} & r_{12} ...
0
votes
0answers
53 views

Is it possible to find $n$ from the sum forming a polynomial? [migrated]

How does one solve for $n$ in: $100000 = \sum\limits_{x=1}^n 1020.2065\ x^{-0.3431}$
0
votes
1answer
86 views

How to use Solve a set of equations [closed]

I have had to revise my question as I have been told it was too trivial for this site - which is somewhat unkind. I have the following set of equations: ...
2
votes
1answer
95 views

Solving for flow speed?

I'd like to use Mathematica to verify the results of a Matlab code that iteratively solves for a flow velocity, u, given some fluid properties and a pressure drop. Ideally, I would like solve the ...
3
votes
1answer
152 views

Very slow mathematica finite differences

I have a simple code which solves an equation by an explicit method (FTCS). It takes mathematica several minutes (mathematica 10.0.2) to finish the calculation while the same code in Fortran runs less ...
3
votes
2answers
175 views

How to propel the integration of time a little bit further? Numerical solution can not evolve to the max time

I try to solve a nonlinear partial differential equation. I obtain a numerical solution which can not continue to the max time I set, I always receive message NDSolve::ndcf: Repeated convergence ...
1
vote
1answer
43 views

Error using NSolve function please help

I have tried to use nsolve to solve this transcendental equation for the bound state of a finite well.. For some reason mathematica is just returning my exact input back to me any ideas on how to ...
0
votes
1answer
59 views

How to solve a linear system of 9 equations with 9 unknowns? [closed]

This is my current code and i'm not sure why it's not working. I am new to Mathematica, though. ...
1
vote
2answers
103 views

Why does this expression take a long time to evaluate?

I was just wondering whether there's an easy to see reason for this expression to take a very long time to evaluate: ...
0
votes
1answer
48 views

NDSolve emitting dvnoarg error [closed]

I'm trying to solve this simple system of ODEs, but it gives me the error "The function v1 appears with no arguments". I've attached a screenshot of the code. I hope someone could help me, I really ...
1
vote
1answer
75 views

Iteration convergence of Newton approximations

I am trying to determine for which initial values Newton's approximation of specific functions (EX: f(x)=x^2 -1)converge and to what numbers it will converge to. *Where Newton's approximations are ...
0
votes
0answers
53 views

Solve Lagrange-multliplier with arrow-security prices with nonlinear (exp) utility function

at the moment I have successfully solved the Demand function for securities in the following model: t=0 current time, 2 uncertain states with same probability in period 2 indexed with i=1 and i=2. ...
1
vote
1answer
177 views

Why won't mathematica solve my two simultaneous equations? [closed]

I'm trying to solve for two unknowns with two equations as follows; ...
1
vote
0answers
66 views

Using Solve without introducing extra variables

First post here. I've tried searching for an answer for this for a few days now, but it seems the search terms (solve, slot, etc) are too generic to be helpful. I'm struggling with understanding how ...
1
vote
1answer
96 views

Quantum Physics question [closed]

I'm not sure if anyone here would be able to help me. But if you know a more appropriate place where I could ask for help, please let me know. So here's the question: And here's my attempt at ...
0
votes
3answers
88 views

Delay difference equation

How can I correctly specify and solve a system of delay difference equations in mathematica similar to NDSolve with regard to delay differential equations? For example if I want to "see" the values ...
0
votes
1answer
35 views

Integrate equation. Variable in terms of another

This might have an easy solution but I am new in Mathematica. I have an equation for which I want to find the solution. My equation goes like: dr/dx = r/x * (2/(k*a^-2*g*x^4*r^(g+1)-1)). What I was ...
0
votes
3answers
98 views

How do I solve for the roots of $\sin(x) - x^2=0$? [duplicate]

I have defined h[x] := Sin[x] - x^2. When I submit Solve[h[x] == 0, x], Mathematica tells me Solve::nsmet: This system ...
0
votes
1answer
40 views

solving PDE with periodic boundary conditions

I want to solve a 2D-PDE that has the form ...
0
votes
0answers
68 views

How can I solve this expression?

I'm trying to solve this expression for A, but I'm not sure how. ...
-1
votes
1answer
41 views

how to write out this equation on Mathematica? [closed]

I have this equation that my manager would like to use on Mathematica, but I've only been learning how to use Mathematica for a few hours. I need to solve for Ax and also plot a graph. Please ...