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
10 views

Simplifying a symbolic product of rational powers

I'm trying to symbolically evaluate a lot of equations that can consist of up to 10 parameters. The form of these expressions is a product/quotient of rational powers of the mentioned parameters, ...
0
votes
1answer
34 views

How to use an output of a Solve function in further calculations? [on hold]

Following is the polynomial equation that gives me a single real root: ...
1
vote
1answer
41 views

Numerically Integrating to find a Maximum using NDSolve

I am trying to numerically find an equilibrium (maximum) of a function using its differential. The following is a simplified version. ...
1
vote
1answer
45 views

Some question on “Reduce”

Is this my mistake? I am trying to solve ...
3
votes
1answer
52 views

Finding linearly independent combination of vectors with a certain symmetry property

I have two linearly independent vectors $v_1$ and $v_2$. Is there a way for me using Mathematica to find two linear combinations $w_1$ and $w_2$ such that: $w_1$ and $w_2$ are linearly independent. ...
1
vote
1answer
50 views

Can someone please help me to state assumption?

I am currently trying to solve under what condition does the following term will be zero? ...
2
votes
0answers
53 views

Aborts and beeps without error warning

I have a piece of code that generates a figure, performing a calculation to generate each pixel. At a certain resolution it runs fine, but after a high enough resolution it fails. Mathematica beeps ...
-3
votes
0answers
19 views

Deriving a simple equation to determine score for matched words against search text [on hold]

This question is related the one that I asked here. I'm working on a small search algorithm that match objects based on word, tag, last access and frequency. Each matched object has a score that is ...
0
votes
2answers
52 views

Eigenvectors inside a maniupulate function

I am trying to make a physics application and it requires that the eigenvectors be taken for a 3x3 matrix. It is my intention that Mathematica never have to deal with the matrices symbolically. ...
0
votes
0answers
28 views

Replace parameter of NDSolve by a Function

I dont know how to replace the paremeter inside of an interpolation function result from NDSolve by a function of another parameter. This is it: I have a ...
2
votes
1answer
87 views

Mathematica unable to solve equation numerically while Wolfram|Alpha can

I want to solve the following equation 2 x == Sinh[x] Mathematica is unable to do so ...
1
vote
2answers
71 views

Solve gives a solution which is contradicted by an example

I have the problem as described in the title. Here is the code: ...
0
votes
0answers
41 views

Calibrating a difference equation system

Sorry for not posting it in the first attempt properly. Consider the simple problem of a first-oder difference equation: ...
1
vote
3answers
156 views

Mathematica Solve function does not solve double exponential

I am trying to solve: Exp[-a Exp[-x/b] - c Exp[-x/d]] == Y to x, and using the command ...
5
votes
1answer
157 views

NSolve missing solutions in Mathematica 10

Running Mathematica 8.0.4 and 10.0.0 on a Windows 8.1 machine. Processed the same code with both kernels: ...
0
votes
0answers
25 views

Calculating Muliti-integral Time-Ordering operator [migrated]

I am trying to solve the time-ordering operator Like this: $S(t)=\mathcal{T}e^{\int_0^tduA(u)\int_0^udvB(v)}S(0)$. How can I calculate S(t) with minimum error?
0
votes
0answers
25 views

How should I state the interval of the variable? [closed]

I have a very complicate equation that consist of 4 variables: x,y,z,w. Now I want set this equation to zero, and solve its roots in terms of x: that is, f(x,y,z,w)=0, solve it in terms of x. ...
0
votes
0answers
28 views

How to solve equations over polynomial rings

sorry if my question is very basic but I don't know what to even search to look it up and the only "obvious" places I thought of had nothing. Some background, for whatever context it might provide. ...
1
vote
1answer
51 views

FindRoot error, Solving equations [closed]

I'm trying to solve this problem but FindRoot function seem unable to find the root when r equals 4. ...
5
votes
4answers
252 views

Symbolically solve and Plot equation involving Tan

I currently have the equation below for a beam with a hinge at various locations, the variable a can vary between 0 and 0.5. $$ Tan\left( {a\sqrt \alpha } \right) + Tan\left\{ {\left( {1 - a} ...
0
votes
1answer
63 views

A problem with “RiccatiSolve::ncsol: Cannot compute a stabilizing solution to the matrix equation ”

I have a SSM ( State Space Model ) and I want to calculate its optimum gains unisng LQOutputRegulatorGains[] command. When I run the code, it solves the equations ...
2
votes
4answers
113 views

Backsubstituting solution into FindRoot and Plot

I want to find roots from a transcendental equation using FindRoot as a function of a real parameter and then plot the solutions vs. the parameter. The following commands work perfectly: ...
2
votes
1answer
102 views

Simple differential equation to solve

Suppose we have this differential equation: $$ x^2 + y^2 + z^2 = \frac{\frac{\partial y}{\partial x}}{x+y+z}$$ I want to find $\frac{\partial y}{\partial x}$ at x=1,y=1,z=1. I tried this code but ...
1
vote
0answers
93 views

Nonlinear FEM and FindRoot

I'm trying to develop a kind of nonlinear FEM application using mathematica to solve a bvp like the following: $$ \gamma(u') ~u^{iv} + 2 \gamma'(u') u''' u''+ u''^3 = f(x) $$ where $u = ...
1
vote
2answers
59 views

FindRoot: getting number of iteration [closed]

I'm using FindRoot to solve a nonlinear system. I'd like to see what FindRoot is doing while computation, something like the display option for Matlab fsolve. At the end of the day, I want the number ...
0
votes
1answer
105 views

Can mathematica rearrange an equation and solve/plot it? [closed]

Suppose we have this equation: $$ sin(x+y+z) = x^2y - wz$$ I want mathematica to plot contours of $x$ with axes of $y$ against $z$ in the limit $w \rightarrow 1$, tried this code but didn't work. ...
0
votes
1answer
81 views

LinearSolve failing to find solution to system of linear equations of 64 variables

I've got a 64x64 Matrix L for which I want to find the solution to the matrix equation L . x == rho. L is defined as ...
0
votes
1answer
91 views

How to calculate the unknown quantity in an infinite series?

I'd like to calculate x value in this equation. Basically, I tried to 2 types of method which are FindRoot and NSolve. But, I have failed the calculation caused by these errors up to now. If ...
0
votes
0answers
37 views

Coupled ODEs with boundary conditions - DSolve Error

I'm relatively new to mathematica and I can't find the error here. I suspect it has something to do with the fact that vx, vy, vz aren't blue on my mathematica - as in, they already have some assigned ...
2
votes
1answer
95 views

NSolve for system of polynomial equations

I would like to find all the solutions to the following system of 8 polynomial equations for the variables w1, w2, w3, w4, w5, w6, w7, w8 ...
0
votes
1answer
91 views

Problems with Solve

I am having a problem similar to the previous question here. Solve either takes forever (I assume infinity) to run or returns an error. I have tried various combinations of using Round, Chop, N and ...
0
votes
2answers
94 views

How to fix problems solving for values of BSpline function?

I generated a spline function called f using the BSplineFunction with domain {t,0,1}. ...
0
votes
1answer
72 views

How can I speed up this multi-equation Solve problem?

I'm trying to solve a set of equations (chemical kinetics for a complex system, but don't worry about that). I ran it for 24 hours and I got no output. Here is the relatively simple code (I want to ...
0
votes
0answers
76 views

To solve an equation

I am trying to solve the equation: Solve[Re[Integrate[(2 c - (r^2) Exp[- I 1.4746])^(0.5), {r, 0, 31.7576}]] == 2.1216, c] I want to integrate an expression in ...
2
votes
2answers
92 views

Extract desired solutions from Reduce

I have the function a = 1 - 3 Sin[theta]^2 Cos[phi]^2; which I solve for 'phi' when $a=0$ sol = Reduce[a == 0, phi] which ...
-1
votes
1answer
93 views

How to find these two intersections? [duplicate]

1.pv=(q1^2+q*^2-q3^2)/[2(q1+q*-q3)] q*=5.3415is the upper limit of q 2.pv+(1-2a)q+2F=2(1-a)C(q) at q=q1 and q=q3。 equation 2 is actually trying to find the intersections of two ...
0
votes
1answer
103 views

How to solve this nonlinear 2 by 2 equations?

I have a equation (x^2 + q1^2 - y^2)/2*(x + q1 - y) + (1 - 2*a)*q + 2*F = 2*(1 - a)*c[q] in q(variable) with parameters q1,a,F and function c(in variable q also, and I define it outside Solve so I can ...
1
vote
1answer
70 views

FindRoot with vector functions

I'm trying to solve a system of non-linear equations with FindRoot, and I get the answer, but also a ...
2
votes
2answers
190 views

How to speed up minimization of function

I have the fallowing code (the functions within that code are replaced by simpler ones, but the code structure is identical): $$$$ ...
0
votes
2answers
62 views

Solve prints message saying that it cannot solve my equation [closed]

I want to solve the fallowing equation: Solve[-(2/x^3) - 1/x^(5/2) - 1/x^2 + (4 Log[Sqrt[E] x])/x^3 == 0, x] Mathematica complaints: This system cannot be ...
4
votes
4answers
292 views

An easier way to find the properties of an ellipse from its equation?

In this Q&A about fitting an ellipse to a set of points, there are multiple answers that generated general equations of the ellipse, like this one by @ubpdqn: However, the steps to find out the ...
4
votes
2answers
186 views

Why doesn't Roots work on a certain quartic polynomial equation?

In everything that follows I am using Roots to get the solutions to the equations. I start off with this equation: $$ \frac{A}{3}x^4 - x^2 + 2ax - b^2 = 0$$ Now ...
1
vote
1answer
116 views

Unexpected result from FullSimplify

In the following simplification why doesn't Mathematica get a zero when asked to compute "Y-Z" eventually? ...
0
votes
1answer
53 views

wolfram mathematica intersection of two surfaces [duplicate]

I use wolfram mathematica. There is a function of two variables which defines the surface z = f(x,y), the second surface is defined as z = const. How to find the line of intersection of these two ...
16
votes
5answers
673 views

Fitting points to tilted, off-center ellipse

I have 24 x-y points that are supposed to form an ellipse. ...
2
votes
3answers
133 views

Solve works with numbers but not number stored in variable

I have the code: ...
2
votes
1answer
46 views

Solve[ ] for 2 variables not returning list of two variables

I type into mathematica: Solve[2 Sin[(Sqrt[3] x - 3 y)/2] == 2 Sin[(Sqrt[3] x + 3 y)/2], {x, y}] expecting it to return a list of pairs of solutions of the form ...
0
votes
1answer
59 views

Cannot solve equation

I just started using mathematica and I'm facing a problem that I just can't solve. I want to solve the following equation: Code: ...
0
votes
2answers
54 views

Solving a system with three equations and two variables [closed]

I am trying to solve some equations with two variables. This is the last step in the process of determining a x tilt angle of a molecule, as well its depolarization ...
3
votes
1answer
267 views

HarmonicNumber problem

I am looking for all the roots of HarmonicNumber, in the domain [-30, 1] and [0, 6000] for the real and imaginary parts, respectively, and where the parameter ...