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

learn more… | top users | synonyms (5)

1
vote
1answer
152 views

Solve a system of non-linear equations

Is there any way to get an exact solution a system of non-linear equations? The system I would like to solve is: $\quad \quad \begin{eqnarray} h_{1}x_{1}=c_{1}\\ h_{2}x_{2}=c_{2}\\ ...
1
vote
1answer
112 views

How can I solve an equation independent of a variable? [duplicate]

Let's say I have the equation $$ ax + b = 0 $$ and I'd like to find a solution that doesn't depend on $x$, so here the solution is obviously $a=b=0$. I could solve this using ...
2
votes
1answer
177 views

How to properly interpret a seemingly contradictory result in Mathematica?

I have a problem with interpreting the results of my notebook outputs. It is important that I do not err with the interpretation. Here is the full input: ...
2
votes
0answers
65 views

Problem with plotting a function that calls FindRoot [closed]

I am having difficulties in plotting the solution of FindRoot to solve 4 variables. I defined a function and then tried tp plot it, but got an error message ...
0
votes
2answers
134 views

Solve returns empty list / running forever

Update: I made a mistake before and corrected the sign in code below in case people wonder what some comments mean. Thank you for those who answered. But I should have said that this is only part of ...
2
votes
2answers
138 views

Why does Mathematica not evaluate the difference recurrence using `RSolve` or `RecurrenceTable`?

Mathematica does not evaluate the following recurrence of two variables using RSolve and only echoes the input: ...
1
vote
1answer
124 views

How to find zeros of 16th degree polynomial with coefficients which contain one symbolic parameter?

I'm trying to find eigenvalues of matrix which is 16x16. Here is a part of matrix: ...
0
votes
0answers
75 views

Inverse Superposition

There are 4 tables that, I have written them as bellow: (m, n, s, and r are orthogonal basis. r.r=n.n=m.m=s.s=1, and m.n=n.r=...=0). a's, b's, c's and d's are coefficients and are numeric values. ...
2
votes
2answers
122 views

Solve[ ] doesn't work with transcendental equations

How to solve x^5-sinx=0 in mathematica? I try in this way: Solve[x^5 - Sin[x] == 0, x],but t doesn't work.
2
votes
1answer
162 views

How can I find all solutions of a complicated expression in a desired interval with Mathematica?

I have an expression which is a combination of Bessel functions: ...
0
votes
3answers
127 views

Problems with finding the real solutions of equation

I am trying to find real solutions of equation using Mathematica 8.0 but there is some problem I don't know how to explain. For example, for the input ...
0
votes
1answer
48 views

Unexpected ReplaceAll behavior with NSolve

I ran into some unexpected behavior using ReplaceAll with an equation of motion using NSolve (or Solve, also). First solving for the initial velocity v0: ...
7
votes
6answers
641 views

Finding where two parametric paths cross?

I have been looking through other parametric equations questions and am still unsure where to start with this one. I am given two functions: ...
3
votes
2answers
86 views

Switching between solutions of a fourth order polynomial

I am plotting the roots of a fourth-order polynomial as a function of some parameter $r$ with the following code: ...
0
votes
0answers
78 views

Finding values of a variable fitting a function and minimizing a list of expressions

I am trying to implement bootstrapping (https://en.wikipedia.org/wiki/Bootstrapping_(finance)) of CDS curve. To implement it I am trying to minimize a series of expressions so that each expression is ...
0
votes
0answers
33 views

why is NSolve giving {y,x} in place of {x,y}? [duplicate]

Why is NSolve giving an inverse set of solution? Is it a problem with my computer only? ...
2
votes
1answer
148 views

How to Solve[] for rational constants?

I am trying to solve a system equations for rational, constant coefficients: ...
-1
votes
1answer
73 views

Find a minimum value which satisfies an equation

I have to find a minimum value of "a" which makes x=-a+b+c, y=-a+b+c^2 positive where a>1, 0 ...
3
votes
1answer
108 views

Inaccurate answer for a system of equations

When I solve the following system of 6 equations by NSolve, it gives me an answer set; however this answer won't make the 2nd equation equal to zero (i.e. when I put the answers into ...
9
votes
3answers
181 views

How to find the solutions to $a+b+c+d=60$?

How can I find all the solutions to: $$a+b+c+d=60\quad (0\leq a,b,c,d\leq 30,\; a,b,c,d\in\mathbb N)$$ I've tried to use Solve[], but it says that there are more ...
0
votes
2answers
85 views

Solving two variable using two expressions each involving summation

I am trying to solve for h1 and h2 using function solve as in below code, Expression in solve has two equation each equates sum ...
0
votes
1answer
71 views

Complex Polynomial roots [closed]

I have the polynomial $p(z)=1-z^3$, I am using mathematica to get all three roots of $p$, say $a, b$ and $c$, obviously $$ 1-z^3=(z-a)(z-b)(z-c) $$ However, mathematica gives a wrong answer by saying ...
0
votes
2answers
65 views

Getting the first solution instance

How do I get Mathematica to stop a solver and give a result as soon as it finds the first solution instance? I tried this: ...
0
votes
1answer
58 views

Solve not returning anything

I have the following function: ...
0
votes
0answers
52 views

Sharp Ratio Maximization, Closed Forms

I am trying to get a closed form for the following first order conditions (n=4): Here's the nb-File. The code is as follows: ...
0
votes
1answer
52 views

Trouble in finding instances of values of variables that satisfy an inequality

Consider the following mathematical expression with complex numbers (phasor) and two variables (lambda and ia2): ...
6
votes
1answer
243 views

Solving $\frac{dx}{dt} = A \frac{ (1-x)}{(t-t^2)} - \frac{(B*x -C*x^2)}{(t-t^2 )*(t-x)}$

I would like to solve the following equation: $\frac{dx}{dt} = A \frac{ (1-x)}{(t-t^2)} - \frac{(B*x -C*x^2)}{(t-t^2 )*(t-x)}$ I have already posted it here, but still it doesn't work for me (I ...
6
votes
1answer
119 views

Closed form of two-layer recurrence

I am trying to find a closed-form expression for $A(0)$, described by the following recurrence forms, as a function of $L$ and $d$: \begin{align} A(\ell) &= 1 + 2^d A(\ell+1) + \sum_{g=0}^{d-1} ...
0
votes
1answer
128 views

Plotting level curves for 2-variable exponential equation (Lotka-Volterra) - how?

I have $$\frac{e^{(d x + b y)}}{x^c y^a}$$ Incidentally, this is the energy integral for Lotka-Volterra as given by my lecturer's notes. I would like to draw the level curves for this equation for ...
1
vote
0answers
72 views

How much time for solving a system of equations?

I wrote the following code for system of 11 equations; however when I run, it shows "Running" and has not converged to any answer after 2 hours. Please let me know whether it is normal or how I should ...
0
votes
1answer
75 views

Problem in solving non linear set of equation?

I am trying to solve a set of non linear equation but using the function nsolve but mathematica is not giving me proper answer. The code is given below. ...
0
votes
2answers
89 views

Exporting and Importing solution sets from NSolve

I have a rather large data set that I need to solve for, then save to my hard disk and import in the same format at a later time. This proves to be tricky. I use ...
1
vote
1answer
88 views

Solve for a variable using expression involving sum of quantities

I am trying to solve for h1 using function solve as in below code, Expression in solve equates sum of two expression. Both left hand and right hand side of expression is the sum of four quantities ...
5
votes
2answers
318 views

DSolve returns a “wrong” solution

This wrong solution exists from mma9 to mma10.1: ...
0
votes
0answers
38 views

How to solve a system of equations which includes vectors? [duplicate]

I'm starting to wonder if this is something that mathematica just can't do? I thought something like this might work: ...
6
votes
2answers
251 views

Solving a two variable two equation trig expression

I am trying to use Solve to get what two angles (A and B) are in a problem I have. ...
1
vote
1answer
62 views

Reducing a system of vector equations

I'm trying to solve a system of vector equations. I know this is solvable since I've done it myself by hand (I reduced it to solving the root of a quartic anyway). I'm trying to do it in Mathematica ...
3
votes
0answers
112 views

Stability analysis of transcendental equation (stability crossing curves)

I am working with a non-linear delay system with three scalar delays. After taking the Laplace transform of the linearized system, the characteristic function is a transcendental equation with three ...
0
votes
2answers
287 views

Solving an equation takes too long

I am trying to solve the following equation func[a, b, c, d, e] == 0 where ...
0
votes
1answer
39 views

Defining a function in terms of a solution returned by Solve

The title is a little ambiguous, but I didn't know how else to put it. What I'm trying to do is solve a system of equations ...
0
votes
1answer
84 views

Use FindRoot to get the root with minimum imaginary part

For example, define test[z_] := Cosh[0.5132928614530164 z] + 0.5934823341977118 Sinh[0.5132928614530164 z] And ...
0
votes
1answer
61 views

List manipulation performance or how to make independent list copy

I have a task to solve some system of equations with NSolve and print graph of it, depends on parameters. Something like this (maybe it is not a good example and does not always have a solution, but ...
0
votes
1answer
102 views

Solve ${\rm BinomialDistribution}(x;\,n_1,\,p_1) = {\rm BinomialDistribution}(a-x;\,n_2,\,p_2)$ in terms of $x$ [closed]

I'm totally a novice with Wolfram software, so please forgive me if the question is nonsense. I want to solve the following equation in terms of $x$: $\quad \quad {\rm ...
2
votes
1answer
171 views

NDSolve doesn't work for this simple differential equations

I try to use NDSolve to do this partial differential equations, but the result is wrong... The source term is a Gaussian pulse as time and an exponential decay with the depth z. The result should be ...
5
votes
2answers
180 views

Reduce applied to vectors doesn't work right?

Reduce[{x,0}=={0,0}, x] gives x==0 as it should, but Reduce[{x,0}!={0,0}, x] gives False, which indicates no solution ...
1
vote
2answers
82 views

Substituting solution into the equation

I need to solve 6*6 equations over and over and put the coefficient into the equations again. But I don not know how? Can anyone help me? ...
1
vote
3answers
156 views

NSolve returning an empty set

Dear Mathematica experts. I am a chemist looking to use Mathematica to solve a system of equilibrium equations. I have a system of 8 polynomial (I think) equations with 8 unknowns, yet when I use ...
4
votes
1answer
159 views

How to solve a conditional inequality?

I am trying to use Mathematica to solve a conditional inequality. Find all (real) numbers $a$ and $b$ such that $|a| + |b| \ge 2/ \sqrt{3}$ and for any real $x$ the inequality $ |a\sin x + b \sin ...
3
votes
3answers
556 views

Finding intersections of two parametric curves

I am dealing with the root finding of two parametric data curves (data below). I have already checked Parametric Interpolation of 2D data, which I found useful for plotting, though it is not adequate ...
7
votes
1answer
226 views

Synchrotron Radiation and ListDensityPlot

I'm trying to reproduce the following plots: As described by this blog entry: Synchrotron radiation As you can see in the linked article, the task is essentially to make a ...