Questions on the analytic and numeric equation solving functions of Mathematica (Solve, Reduce, NSolve, FindRoot, DSolve, RSolve, etc.).
2
votes
2answers
124 views
0
votes
1answer
109 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 ...
4
votes
2answers
73 views
Solution of equation with power series (perturbation)
So I need to use Mathematica to find the solution of $y=x- \epsilon \sin(2y)$ as a power series in terms of $\epsilon$. I'd assume I'd need to create an equation $f=x-y- \epsilon \sin(2y)$, then ...
1
vote
1answer
79 views
finding poles of a function
Is there a command to find the poles of a function $f=f(z)$?
example: let $$f(z) = \frac{1}{z^2-1}$$ then we know that the poles are at
$z=\pm 1$ but is there a special command in mathematica to do ...
2
votes
1answer
87 views
Problem with Sinc[x] function and rounding
I seem to be having some trouble with the Sinc[x] function, and I think it's due to rounding, but I'm not sure.
The code is below, with relevant constants:
...
2
votes
0answers
75 views
Solving a nasty equation
Here's an equation that I need to solve for $t_k$
$$
\theta_0 = \tan^{-1}\left(\frac{2(w_x - m)}{p - g {t_k}^2 - 2 t_k w_y}\right) - {\frac{1}
{r}}
\left( \left(\frac{m}{t_k}\right)^2 +
\left( ...
0
votes
0answers
40 views
NMinimize and FindRoot Issues with System of Equations [duplicate]
I am trying to solve a constrained optimization problem with a system of transcendental equations and am running into issues with NMinimize. I have a system of equations (...
5
votes
3answers
133 views
How do I find the intersection of a closed 3D curve given by numerical data with a specified plane?
I have a list of 3D data points which form a closed curve. My own data can't be easily generated analytically, but the qualitative behaviour is well represented by a parametric curve families such as ...
4
votes
1answer
92 views
How to add equations' left and right sides together?
If we have two equations E1 and E2, and instead of using Solve to solve it, we simply need to manually add them up which would allow some simplification that could ...
1
vote
0answers
69 views
Problems with Simultaneous Equation Solving
Let me first explain what I am doing and then I will explain the problem that I can't figure out. I am basically trying to solve 2 equations for 2 unknowns (a1 and ...
-1
votes
0answers
31 views
NDSolve: Equation or list of equations expected instead of False in the first \ argument [closed]
I do not know why this here will to work.
...
6
votes
2answers
106 views
Finding y given x from an interpolating function
I would like to put a dot on the point of a curve that has a specific y value but I don't know the x value.
A simple example of my code is
...
1
vote
1answer
59 views
Corrected: Solve[] cannot solve simple hyperbola equations?
Is Solve[] very inefficient in solving equations involving square roots?
The input below attempts to find out the explicit expression of either x or y in terms of other variables {x|y, a, c}, and c ...
0
votes
1answer
55 views
2
votes
1answer
157 views
Distance between 3D curves
I would like to determine the distance bewteen two representations of the Lorenz Attractor. I have two 3D representations for different initial conditions and I want to calculate the distance between ...
-1
votes
0answers
109 views
Solve seems to return wrong answers when handling expressions with more than 5 variables
When working with Mathematica's Solve function, it seems to return wrong answers when I solve polynomial equations involving 6 variables.
I have defined a function ...
0
votes
0answers
100 views
Searching for roots of complex function
I'm searching for roots of complex function
$$
2\imath q \ln(-2\imath k)+\imath\pi-2\imath \Im(\ln(\Gamma(1+2\imath q)))+\ln(\frac{\Gamma(1+\imath q-\imath q x/k)}{\Gamma(1-\imath q-\imath q ...
6
votes
4answers
309 views
Am I missing anything? Solving Equations
I want to know what $ a^4+b^4+c^4 $ would be when
$ a+b+c=1, a^2+b^2+c^2=2, a^3+b^3+c^3=3. $
I tried
...
0
votes
2answers
119 views
Solving numerically system with Mathematica
I'm trying to solve the following system with Mathematica:
...
6
votes
3answers
157 views
How to get the correct answer when solve this equation?
I want to find the values of the parameter $m$ to the graph of the funtion $$x^4 - 2 m x^2 + m + 1$$ has three extremal points make an equilateral triangle. I tried
...
3
votes
1answer
120 views
Finding the largest integer that cannot be partitioned in a certain way
I want to use Mathematica to solve the problem:
Find the maximum $k$ such that $6x+9y+20z=k$ does not have a non-negative solution.
I tried FrobeniusSolve. ...
0
votes
1answer
44 views
Solving one equation, then inputting the values into another for NonlinearModelFit
Considering the equation
a*x^3 + a*x^2 + x + b == 0
I'm looking to find the best value for a and ...
2
votes
3answers
248 views
Solve and plot an equation that is dependent on a transcendental equation
I am trying to plot a function that uses the values of a transcendental equation as its input values:
y = Tanh[(2 y + x)/2.5]
z = 2.5 * Log[2*Cosh[(2 y + x)/2.5]]
...
4
votes
3answers
160 views
Inverting a Spline-Function (Bezier or BSpline)
I would like to use a Spline-Function to describe a transformation from one range of reals to another, that is I would like to have a function which maps a value $y$ on $x$ and for simplicity let us ...
0
votes
1answer
37 views
Constraining solution's sign with NSolve
I am solving some equations in 4 variables, however, there are many solutions which are basically the same but changing relative signs of each other ... i.e. {x->-1,y->1} and {x->1,y->-1}.
...
0
votes
1answer
91 views
How can i get the solution of complicated equation?
This is the equation about zeta. NSolve[equation] could not solve this equation. (I think it is too complex to solve by NSolve.)
I want to know how can i solve this equation such a complicated ...
-1
votes
0answers
14 views
Statistics Question [migrated]
This is probably super simple to most of you on here, but I was chatted by a friend earlier with a question. It reads just like this:
...
1
vote
0answers
45 views
Is this being simplified correctly? [closed]
I'm unsure if this is a bug or if it's a case of Mathematica not doing quite what I expect it to.
...
5
votes
0answers
51 views
Faster way to perform SameQ[Reduce[…], Reduce[…]]
I'm have some expressions that I need to confirm the equality of. SameQ[Reduce[...], Reduce[...]] works like a charm for the more simple expressions, however when ...
5
votes
1answer
127 views
Solving an inequality that contains Log expressions
How can I solve the following inequality:
Log[1/2 + c^2] > (1.4) (30^5) 2^(4.5) 9 (0.6) (2.8) (1 + Log[3]) (1 +Log[ Log[c + 1]])
?
I tried ...
1
vote
1answer
75 views
How to get a solution set of a nonlinear system of equations?
I'm trying to find the solution set of {x, y} variables for the following system of equations:
...
3
votes
1answer
86 views
Cannot solve system of linear equation sums?
I cannot get mathematica to solve:
The problematic code:
...
5
votes
2answers
257 views
Find all the integer numbers $a$, $b$, $c$, $d$, $e$, $f$, $k$ to this equation have three integer different solutions?
How to find all integer numbers $a$, $b$, $c$, $d$, $e$, $f$, $k$ that belong to interval $[-10,10]$, so that the equation $$\sqrt[3]{a x + b} +\sqrt[3]{c x + d} + \sqrt[3]{e x + f} =k$$ has three ...
9
votes
1answer
214 views
Efficient way to solve equal sums $x_1^k+x_2^k+\dots+x_5^k=y_1^k+y_2^k+\dots+y_5^k$ with Mathematica?
I need to solve the system of equations, call it $S_1$, in the integers
$$x_1x_2x_3x_4x_5 = y_1y_2y_3y_4y_5$$
$$x_1^k+x_2^k+\dots+x_5^k=y_1^k+y_2^k+\dots+y_5^k,\;\; k= 2,4,6$$
I used a very ...
1
vote
0answers
59 views
Bounds on random number
I have a Markov Chain Monte Carlo code that uses a chi squared function to fit some data.
I am running into an issue now with getting unrealistic values for some of the free parameters
in the code. ...
16
votes
1answer
409 views
The Orbit and Perigee of the Flamsteed comet
Historical context
This year we have the 330-th anniversary of the Battle of Vienna - one of the great formative events of European history, it took place on September 12, 1683.
Kara Mustafa, Grand ...
2
votes
1answer
89 views
Reducing exponential inequalities fails
I am quite stumped by this problem :
Reduce[ N^(x-y) <1 && N > 0 , x, Reals]
gives the expected result
...
-1
votes
1answer
96 views
Solving for variables in a series of nonlinear equations [closed]
I have a nonlinear expression in five variables. I want to use Mathematica to solve for three of the variables. I have a series of points giving values of x an y and I am trying to solve for a,b, and ...
0
votes
0answers
82 views
draw a graph of a polynomial function with variables in the denominator [closed]
I have an equation f(u,z1,z2)=0, which is a long and complicated polynomial function with u in denominator.
...
0
votes
0answers
50 views
Collect and factor equations with certain terms
Collect user defined terms from a symbolic algebraic expression
...
4
votes
2answers
153 views
find where 3 inequalities are simultaneously greater than zero
I have 3 functions: f11[l], f12[l] and f13[l], and I would like to know for which values of ...
1
vote
1answer
90 views
Prandtl-Meyer function
I'm trying to solve for Mach number based on the given Prandtl-Meyer function, however I keep getting odd error.
Here is my code:
...
1
vote
0answers
93 views
I can't solve this set of equations
I am having trouble solving a set of equations in mathematica. I do not get any errors, but i don't get any answers as well.
I have some restrictions on my parameters and variables in the equations ...
4
votes
3answers
225 views
Solve for the intersection point of 3 surfaces
Basically, I have three 2-torus (tilted) in 3-dimensional Euclidean space. They are expressed by parametric equations:
...
1
vote
2answers
111 views
Count and plot the number of solutions in an interval
I have equations depending on one or more parameters and I want to find and plot the regions in the parameters space in which there are a specific number of solutions.
For definiteness let's ...
1
vote
1answer
183 views
solving a cubic equation
I need to find the minimum $r$ and the maximum $k$ of the following cubic equation for which there does not exist three distinct real roots.
$rx^3-rkx^2+(r+k)x-rk=0$.
Is it possible to find such $r$ ...
0
votes
1answer
132 views
How can I solve this nonlinear system with 3 equations and 3 unknown? [closed]
I have this system with 3 equations and 3 unknowns:
...
0
votes
0answers
98 views
Solve equations real and imaginary part separately
For my system of equations, the procedure described in Solving complex equations of using Reduce works no more. How can I separate the real and imaginary part of ...
2
votes
1answer
67 views
Error/warning when using NSolve for simple equation
I am using NSolve to solve an equation, as shown here:
...
2
votes
1answer
65 views
Finding the root of a nested function with small values
I have reduced an error in my program to this line of code:
FindRoot[Nest[# (1 - #) k &, 1/2, 2^4] - 1/2, {k, 3.5}]
It works for $2^1, 2^2, 2^3, 2^4,$ but ...
