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

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0
votes
1answer
42 views

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

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
34 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
38 views

Need Help with solve function [on hold]

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
36 views

FindInstance—why doesn't it work with my expression? [on hold]

I want to find arbitrary solution of a system of equations: ...
0
votes
1answer
60 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
45 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
75 views

Using functions in Solve [on hold]

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
51 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
113 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
86 views

Issue with NSolve for solving six equation and six unkown [on hold]

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
50 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
30 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
70 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
53 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
57 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
157 views

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

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
81 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
69 views

Errro in plotting the results of FindRoot

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
36 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
34 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
58 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
204 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
48 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
63 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
355 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
40 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 ...
1
vote
1answer
60 views

Solving equations with subscripted variables

A student of mine tried: Solve[1/R == 1/Subscript[R, 1] + 1/Subscript[R, 2], R] which did not work. We then tried: ...
0
votes
0answers
25 views

Quickly Solving a High-Order Root System of Equations of Arbitrary Form

I have the following system of equations that involve some rather complicated exponents: $$ \left\{\frac{\mathit{a} \sigma ^{41/34}}{\mathit{m}^{8/119} ...
1
vote
1answer
60 views

I can not solve this equation for recurrence [closed]

Use RSolver to solve RSolve [{f [n + 1] == f [n] + 2 n + 1, f [1] == -3}, f [n], n] but I do not get solution Edit my solution
0
votes
1answer
61 views

Rearranging Equations

I'm very new to Mathematica and I want to do something I would consider very simple, but cannot find the commands for. In essence, I want to just simply rearrange the variables of an equation around ...
0
votes
0answers
46 views

How to get x = 1.234 from {x -> 1.234}? [duplicate]

I'm a complete beginner in Mathematica (started a couple of days ago). I've solved a function using "Solve" and the result is this one: Out[1] = {x -> 0.000942939} How do I get the 0.000942939 ...
0
votes
0answers
46 views

Implement Lagrange Multiplier in NDSolve

I have a Lagrange function $L$ that depends on a couple of complex, time dependent coefficients $A_{\alpha,j,n}$ where $\alpha \in \lbrace{1,2\rbrace}$, $j,n \in \lbrace{1,\ldots,N\rbrace}$ where $N$ ...
0
votes
0answers
61 views

Solving numerically a system of equations using different methods

I will use, as an example, the simple Henon-Heiles potential ...
1
vote
2answers
85 views

Bessel-like equation problem with NDSolve

I am trying to solve the following nonlinear ODE, but Mathematica takes forever to give a result. Any idea why? ...
9
votes
2answers
180 views

NSolve finds real-valued results in version 9, but not in version 10

UPDATE Reals also was used in the code. Actually, I tried the following simple piece of code. ...
1
vote
1answer
58 views

how to replace one calaculation result to another one in a loop?

I am doing the calculation in a loop. I gain a digit for rzin in ...
1
vote
1answer
49 views

Approximating exponentials in a nice to read format

I need to make some approximations, basically I have something like $$ e^{i*a} = -0.735145 + 0.67791*I $$ and I want to approximate this to something that is easily readable, like $$ ...
0
votes
0answers
32 views

Combining two NDsolves results in “The search has encountered a complex value…” and no solution

So far I used to seperate NDsolves to solve a system of coupled differential equations, where the first NDsolve yields the Boundary conditions for the second NDsolve ...
4
votes
4answers
394 views

Solving complex equations with variable exponents

How would I go about solving $(1+i)^n = (1+\sqrt{3}i)^m$ for integer $m$ and $n$? I have tried ...
9
votes
1answer
172 views

Using Solve to solve the equation $x^{1/3}=-1$

I am curious why this command returned no answers: Solve[x^(1/3) == -1, x] Gives this output: (* {} *) I was able to get ...
3
votes
3answers
251 views

Number of solutions for inequality

Please explain me how can I calculate a number of possible solutions for such inequality and obtain those values: 3x + 7y + z <= 198 where ...
0
votes
0answers
57 views

Eliminating one function from non-linear PDE

Is there any solution to eliminate function p[x,y] from these two equations which are equal to zero (diff1=0 and diff2=0) where c and d are constants. I need one equation where should figure just ...