Tagged Questions

71 views

Replace $z$ with interpolated function and plotting

I start off with this equation $z(x,y) = sin(xy)$. I create an interpolation from $0 < x < 5$ and $0 < y < 5$. I then use this interpolation on a simple function $w(x,y) = x + y + z(x,y)$ ...
176 views

How do I feed data points into an equation to solve NUMERICALLY?

I start with this equation and solve it numerically for $z(x,y)$ in the range $1 < x < 5$ and $1 < y < 5$: $$\frac{3}{xyz} - 2x - 3y - 5z = 0$$ Then using the data points of $z$ above, ...
77 views

Find roots of a function involving Bessel functions

I'm trying to find the roots of a function involving Bessel functions. Here is my code ...
83 views

Find solutions of equation involving Bessel functions

I'm new in Mathematica and I'm trying to find the solutions of this equation involving Bessel functions $$\eta \frac{ J_{n+1}(\eta a)}{J_n(\eta a)}+\chi \frac{ I_{n+1}(\chi a)}{I_n(\chi a)}=0$$ ...
103 views

Eliminate z from two equations in x, y, z and plot y as a function of x [closed]

I have this equation to begin with: $$1 - 3 x y = 5 z - 2 x$$ I want to solve this equation for $z(x,y)$, then plug $z(x,y)$ I plug $z$ inside a second equation: $$y = 7 x z - \frac{z}{x}$$ ...
35 views

Resources/ best practices for exploratory economic theory work

This is a little general, so I will try to make it as specific as possible. I used Mathematica a fair amount to derive and check analytical solutions to problems in theoretical economics. Lots of ...
229 views

How do I plot the differential of this function?

Suppose I have this function: $$z(x,y) = \left| \frac{ \frac{1}{3x +iy} -2x}{iy + \frac{1}{x}} \right|$$ I want the contour plot of $\frac{\partial z}{\partial x}$ with axes $(x,y)$. Tried this ...
92 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 ...
37 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 ...
121 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. ...
764 views

Fitting points to tilted, off-center ellipse

I have 24 x-y points that are supposed to form an ellipse. ...
84 views

Graphical solution of a a two-variable system containing an equation and an inequality

I'm currently studying atmospheric-gravity waves and their dispersion relations. I want to have look at values of $(x,y)$ that solve the following system : \label{}(1) \left\{ ...
261 views

Projection of curve 3D (x,y,z) on the x-y plane

I have a following systeme : \left\{ \begin{array}{rcr} (\beta+\frac{1}{2}\delta^{2})\nu_{1}(u)-\delta\nu_{2}(u)+\nu_{3}(u)& = &0\\ ...
73 views

Trouble plotting a function constructed using NIntegrate and FindRoot

Here is my code: ...
58 views

Using NSolve in a function, selecting one indexed result and using it to plot another function containing a function containing the indexed result

I have a problem using the result pcvar[g] g e (0,1) in the plot cvar1. In the plot cvar I can use it. It must be somehow connected to clearing p in the definition of pcvar[g]. I am gratefull for any ...
175 views

Function with a sharp resonance which Mathematica fails to integrate. Why?

I'm a new user of Mathematica and I'm trying to use it to calculate the collisional cross-section as a function of energy for a given potential and decay rate. I know that the resulting function ...
159 views

Solving System of Nonlinear with Three Differential Equations

I've been trying to solve a system of nonlinear differential equation, but the conditions are a bit weird. Two of the differentials equate to the same equation, but have different boundary ...
96 views

marking the points of x-intercept on a plot

OK, I have a nice plot of some oscillating motion. I can read some stuff off the graph, but I thought it would be cool to show a dot where the curve hits the x-axis and a little label showing the ...
377 views

1D quasicrystal: points on a line nearest to points on a lattice

I have a simple lattice / line manipulation: ...
181 views

Problem with Plot and ParametricNDSolve

This is my first question on this site, I hope it is written in an understandable way. Let's start. My aim is to plot a certain parametric region, with $x$ and $y$ coordinates given by the following ...
60 views

Finding undetermined coefficients with boundary conditions

I have 2 equations which are; To[x_] := c1 E^(-a1 x)/2 + c2 E^(a1 x)/2 + a2 Tu[x_] := c3 E^(-a3 x)/2 + c4 E^(a3 x)/2 Tu equals almost zero ...
50 views

How to find the x-axis intersections/zeroes of a parametrized integral? [duplicate]

Consider the situation with this functions, ...
121 views

Poincaré section for 3BP

I try to plot the PoincarÃ© section for the 3BP i use the following code that works very well: ...
160 views

intersection between function and plane

I try to solve a ODE system of equations and i want to plot the intersection of the 3D solutions with a costant plane. To do this i use the follow code: ...
120 views

2 Equations continuous at a point

I want to get continuous point between two equations. My equations are: ...
100 views

Plotting the results of a system of equations

I believe this is a question of more list manipulation than plotting, but I hope you could help me. I solve numerically a system of equations of 3 variables, take only real solutions where one of the ...
130 views

invert system of two parametric ODEs and plot results of do-loop

I can solve this system of parametric ODE (u is the parameter,while g,e and ...
136 views

How to solve an equation with two variables in Mathematica

If I solved an example equation like |x|+|y|=1 numerically, I would to get a 90Â° rotated rectangle. If I was to plot the equation, it would result in an image like ...
164 views

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189 views

Plot a table of ranges

I have table with values like: t = {1.234 <= a <= 2.345, 3.42 <= a <= 5.67, ...} and I want to plot this table, the ...
163 views

Plotting double inequality only for integer values

RegionPlot is plotting for all values. And using ListPlot I can only evaluate one inequality. How can I plot this type of ...
125 views

Discrete inequality plotting

I have an equation like this: $${20 \choose k}\cdot \sum_{i=0}^k {k \choose i}\cdot i \leq 1+f$$. I want to plot this inequality as the dependency between k and ...
235 views

130 views

automatic processing of numerical results in Plot

First I want to solve an equation $F(x,y)=0$ for $y$ by supplying a value of $x$. (suppose obtaining the analytic form of $y(x)$ is too difficult) Then I want to plot root $y$ (numerically calculated) ...
90 views

Gaps in plots of equation solution from parameter

I'm trying to plot solution of system of equations as a function of parameter ...
179 views

Plot the solution complex transcendental equation

I'm trying to plot an implicit function satisfying a complex transcendental equation. The code is the following: ...
106 views

InputField equations and Solve

I'm trying to get this piece of code to work: ...
536 views

Alternate parameterization of a line

There are several ways to specify a line. In Mathematica's graphics, it is done by specifying two points and then connecting the points with the Line command. But ...
448 views

How to find the zero of a function?

I want to find out when a function has a real root. I first made a RegionPlot3D when the function is zero. ...
127 views

FindMinimum gives wrong solutions inside a loop

I have a density function $\rho(r,z)$ and I want to calculate the minimum distance $d_{min} = \sqrt{r^2 + z^2}$ from the center (0,0) in which $\rho$ becomes negative. The easiest way is to find where ...
387 views

How to increase Maximum number of steps in any other functions except NDSolve?

I want to plot an output response from a state space model. I use StateResponse[] to calculate it and then plot it. When I run my code, I face this message: ...
494 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 ...
95 views

Cannot Plot Output of Solve

I'm trying to plot the output of the following function t2[x_] in ...
472 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 ...
1k 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]] ...
321 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 regions in the parameter space in which there is a specific number of solutions. For definiteness let's consider a ...