What is Mathematica: Definition and 1000 Discussions

Wolfram Mathematica is a software system with built-in libraries for several areas of technical computing that allow symbolic computation, manipulating matrices, plotting functions and various types of data, implementation of algorithms, creation of user interfaces, and interfacing with programs written in other programming languages. It was conceived by Stephen Wolfram and is developed by Wolfram Research of Champaign, Illinois. The Wolfram Language is the programming language used in Mathematica.

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  1. D

    Mathematica Cobb-Webbing Mathematica: Solving rNt+1

    How can I get Mathematica to construct a cobb webb for $$ N_{t+1} = \frac{(1+r)N_t}{1+rN_t} $$
  2. N

    Mathematica Is there a function in Mathematica for binning 2D data?

    Hi Say I have a data set (x_i, y_i) such as of the form { {4.4077, 8.41282*10^-7}, {9.39964, 3.3636*10^-6}, {14.3781, 7.56237*10^-6}, {19.3462, 0.00001343}, {24.3073, 0.0000209557}, } The first coordinate is time, the second a weight. The sum of the weights equal 1, so I am...
  3. M

    Mathematica Mathematica Slows Down with Repeated Evaluation

    I'm trying to analyze a fairly large (order 10^3) collection of PDB files to look for cation-pi interactions for a class. This requires me to parse each PDB file into a table which gives the position of each atom in the file. To do this, I've written the following code...
  4. S

    Mathematica Mathematica: speeding up NSolve

    Hello everyone! I have a system of equations which I am trying to solve in order to 13 dependent variables. Yet, I am only interested in the answers which are real positives. In my code I have implemented a way to select only the answer which satisfies this constraint: Cases[ NSolve[...
  5. N

    Mathematica Solve ODEs w/ Mathematica & Compute Derivative of Niles

    Hi I have a system of ODEs of the form dx/dt = v dv/dt = a = C*f(x), where C denotes a constant and f(x) is some function of x. This system is easy to solve using (e.g.) NDSolve[x''[t] == C*f(x), x[0] == 0, x'[0] == 0}, x, {t, 0, tMax}]; I need to use the derivative of the solution x[t]...
  6. K

    Mathematica partial differentiation weirdness

    I am checking my homework with mathematica, but sometimes when I write stuff like D[(x/((x^2 - y^2)^0.5)), y] , which is supposed to give me the partial derivative of x/((x^2 - y^2)^0.5) with respect to y, i get answer like: (1. x y)/(x^2 - y^2)^1.5 which is right, except for the...
  7. I

    Mathematica Mathematica: Having issues with simple DE system

    I have a system of three DE's and one other definition. The system I'm working with is given in the attached equations.nb. I've attempted two methods to solve the system. The first is by assuming steady states on the three DE's, setting them to zero, and using algebraic manipulation to...
  8. N

    Mathematica Plotting y''[x] vs. y[x] in Mathematica with NDSolve

    Hi Say I solve the following differential equation in Mathematica: s = NDSolve[{y''[x] + Sin[y[x]] y[x] == 0, y[0] == 1, y'[0] == 0}, y, {x, 0, 30}] Plot[Evaluate[{y[x], y'[x], y''[x]} /. s], {x, 0, 30}, PlotStyle -> Automatic] The last line plots the solutions vs. x, but how can I...
  9. Barnak

    Mathematica Prob with NDSolve in Mathematica

    How can I show the regular part of the solution of a differential equation, numerically solved with NDSolve, if there's a singularity on the curve ? I know how to use NDSolve and show its solution, but Mathematica gives a bad curve after some point (singularity jumping). I don't want to show...
  10. C

    Mathematica How can I manage memory usage while plotting 3D functions in Mathematica?

    I'm trying to plot some 3D functions in mathematica, but each time I evaluate the cell, more and more RAM gets eaten up. How do I clear the memory to keep this resonable? My PC almost crashed because I ate up all the memory. I tried ClearAll and ClearSystemCache[] and it didn't work. I'm new...
  11. R

    Mathematica Sow within While Loop (Mathematica)

    I posted this in number theory "Ramsey Primes" but I don't think this qualifies as an improper use of this forum. I need help with my code. My code for Mathematical is short so I will include it below for reference. There are some flaws. For instance the Reap/Sow function generates a list of the...
  12. S

    Mathematica Mathematica: Multiplicative Inverse of an integer using modulo

    Hello everyone, I've been trying to figure out how to obtain the multiplicative inverse of an integer in Zn in Mathematica but I haven't found a way. Is there a way to do this anyone can help me with?
  13. Barnak

    Mathematica Problem with ParametricPlot3D in Mathematica

    I'm having an output quality problem with ParametricPlot3D in Mathematica 7. I need to show a complicated curve found by numerical integration of a differential equation (using NDSolve), and export the curve's graphic (from ParametricPlot3D) to PDF, so I can use it in another application. I...
  14. D

    Mathematica Solving an Equation for u: Can Mathematica Help?

    I am using Solve to try an solve this equation for u. Solve[ru(1-u/q)-(1-E^{-u^2/t}) == 0, u] However, Mathematica keeps telling me that system can't be solved with the methods used by solve. Is there another way to do it?
  15. A

    Mathematica Finding Minimum Value with Mathematica

    ∂ω2 = (1-cos2(Δt)e-2γ(t))/(nTtsin2(Δt)e-2γ(t)) n,T are assumed as constants. How can I use Mathematica to find the values of Δ and t that will give the minimum values for ∂ω2 ?
  16. G

    Need a code to construct an antisymmetric tensor with Mathematica 6.

    Hello! I'm doing a code in Mathematica 6.0 in order to calculate a contraction of indices with the Levi-Civita tensor (in six dimensions) and an antiSymmetric tensor A[m,n,p] (it has 3 indices running from 1 to 6). For example in order to turn A into an antisymmetric tensor, I wrote something...
  17. G

    Mathematica Mathematica: I made a program, but can't manipulate it. Please help

    The program I wrote accepts a certain number between 3 and 18. Then it returns the ways this number can be obtained by throwing three dice simultaneously and adding the face values. I want to manipulate this number, :biggrin: but can't achieve it using the ordinary code of manipulation...
  18. A

    Mathematica Custom Mathematica Shortcut: Copy as LateX

    This can be very useful, so I thought i'd share. If you edit the > Wolfram Research\Mathematica\8.0\SystemFiles\FrontEnd\TextResources\Windows\MenuSetup.tr file you can make Strl+Shift+C copy not plain but in LateX format. Very useful. Look for the line in the file that says "&LaTeX"...
  19. N

    Mathematica Mathematica Matrix creation help

    Hi, I have a whole bunch of data (Arrays of the form H1, H2, H3 etc) that I want to crunch to create 10 more variables. I did: For[i=1,i<23,i++,{f1(i),f2(i),..,f10(i)}>>>"temp.mx"] Where fj(i)= fj(H1[[i]],H2[[i]],...), the functions are different functions of the numerical data I...
  20. D

    Mathematica Plot Phase Planes ODEs Mathematica

    How can I plot the different phase planes for a system of ODEs in Mathematica?
  21. A

    Mathematica Plot Gamma Function with Mathematica

    I have a gamma function in the form of Gamma(s-1) where s can take only positive values. How can I plot this function for different value of s using Mathematica ?
  22. K

    Mathematica Scaling Axes in Mathematica for ParametricPlot

    Hi, Am plotting a graph and need to scale the axes so that i can take my range of 'x'-axis values from -1 to infinity. I shall provide script, but i am using the ParametricPlot command. ParametricPlot[tab2, {up, -1 + 10^-7, 10}, AxesLabel -> {"\[Rho]", "u'"}, PlotRange -> {{-1, 2}...
  23. T

    Mathematica NDSolvederlen: - Mathematica error - TOV equations

    Hi All, I'm trying to solve a set of three coupled ODES. I have given initial values for all functions, and I believe I have entered in the code correctly but I still get this error telling me that the derivative operator is not the same length as the number of arguments. What does that...
  24. D

    Mathematica Mathematica Plot to Latex Document

    How can I put a Mathematica plot in my Latex document?
  25. N

    Mathematica How to create a database in Mathematica

    Hi All, I have to solve a system of non-linear equations for a wide range of parameter space. I'm using FindRoot which is sensitive to initial conditions so I have to do it by hand and by trial and error and plotting, rather than putting the equations in a loop or in a table. So what I...
  26. T

    Mathematica Mathematica Help - Plotting equation with i

    I cannot seem to make mathematica plot the following equation correctly: r[t_] = 3 Cos[t] + iSin[t]; plotbeta = PolarPlot[r[t], {t, -Pi/2, Pi/2}] I have used the capital I to no avail; I have used * to indicate multiplication. It plots the curve without a problem when I leave out the i...
  27. N

    Mathematica Mathematica storing output generated from a loop

    Hi, I am running FindRoot on three variable system of three non-linear equations for a variety of parameters (four) and a huge range of parameter values. A simplified example is as follows: one parameter and one variable: I want to solve the equation f(x,a)==0, where 'x' is the variable...
  28. S

    Mathematica List of CAS: Mathematica, Maple

    Hello All, I would like to ask about experience in general math as well as general engineering software. At university time we used in different departments 1. Mathematica http://www.wolfram.com/ + add on http://www.fgg.uni-lj.si/Symech/ 2. Maple http://www.maplesoft.com/ + add on Mechanics of...
  29. G

    Mathematica [Mathematica] Subnormal numbers handling

    Hello all :) I have a matrix which I diagonalize giving me a list of eigenvalues lambda. Those are complex numbers. After that, I calculate Exp[-lambda] and my code goes on. For some parameters in my code, some lambdas have very large magnitude so that the exponentiation leads to...
  30. N

    Mathematica Mathematica FindRoot exploration of parameter space

    I am solving three non-linear equations in three variables (H0D,H0S and H1S) using FindRoot. In addition to the three variables of interest, there are four parameters in these equations that I would like to be able to vary. My parameters and the range in which I want to vary them are as follows...
  31. 7

    Mathematica How to get a special coordinates {x,y} from a matrix in MATHEMATICA.

    Hello every one, this question for a mathematics experts... Suppose we have the matrix M = \left| {\begin{array}{cccc} 9 & 6 & 0 & 1 \\ 3 & 7 & 2 & 5 \\ 1 & 0 & 2 & 8 \\ 8 & 8 & 1 & 0 \\ \end{array} } \right| and we want to print only the coordinates that equal to 0...
  32. T

    Laser Heating & Mathematica Problem

    Hi the problem i am dealing with is that we want to heat samples up with a laser in our lab. For estimating the required laser power, as you know better than me, the main loss will be the heat diffusion in the material. My heat equation is in the following: \frac{du(x,y,z,t)}{dt} -...
  33. P

    Mathematica Mathematica maximize element extraction from list

    Hi guys, I think this is a simple question for mathematica experts. How can I maximize the extracted value from a list given a index that has to respect some constrains? For example: S = {4,2,3,5} Maximize[{Extract[S,x], x<= 3, x>=1},{x}] I would like 4 is returned instead of...
  34. P

    Mathematica Mathematica, NMinimize extract data from list

    Hi guys, I am struggling again NMinimize. This is my problem: I am creating a model by using goal programming, my problem now is given a list of list i.e a matrix defined in this way S = {{5, 2, 7, 9}, {1, 2, 3, 4}, {3, 1, 2, 4}} extract from the first list {5,2,7,9} a number by...
  35. S

    Mathematica Mathematica: Infinite expression error when using NDSolve

    Dear all, If someone could help me solve this mathematica NDSolve problem, that would be really nice. Here is a related, simpler problem to the one I am having. Suppose I want to solve the nonlinear ODE \left(2 r + f(r) f'(r) \right) (1 + f'(r)^2) + r f(r) f''(r) = 0 subject to the...
  36. A

    Mathematica Mathematica: Fourier Transform by hand of sin

    Hi, i do not understand why i can find the FT of sin in mathematica using the built in function but not by integrating, even thoiugh they should be the same: Integrate[Exp[i(ω-ω0) t,{t, -∞, ∞}, Assumptions ->ω0 el Reals && ω el Reals] but the statement FourierTransform[Sin[ω0 x]...
  37. N

    Mathematica Mathematica - Showing iterations graphically

    I'm trying to do this: Suppose I have some iterative function $x_{n+1}=\sin(x_n)$. I want to demonstrate an iteration on a plot by graphing $y=\sin(x)$ and $y=x$, then drawing lines from the graph of x to the graph of sin x, like in this page...
  38. C

    Equation for this graph - Mathematica

    I think its a variation of a cosine function, but i have no idea what Does anybody have any idea?
  39. L

    3space graphs on Mathematica 8

    (note for editor; this is not a homework problem, this is bred out of my desire to visualize 3space) Hello fellows, I am hoping that somebody can help me. I've asked multiple teachers and tutors, but nobody can solve my seemingly very easy problem. I am taking a course in multivariable...
  40. S

    Mathematica [Mathematica] How to use this code?

    I have a notebook with the following code in it: GratingFrame[n_, c_, k_, \[Theta]_, \[Phi]_] := Graphics[Raster[ Table[0.5 + 0.5 c Cos[ 2 Pi k (i Cos[\[Theta] Pi/180]/n + j Sin[\[Theta] Pi/180]/n) - \[Phi] Pi/180], {j, 1, n}, {i, 1, n}]]]...
  41. Y

    Mathematica How to Plot Large Data Sets in Mathematica?

    hi i compile a c++ program and after compiling it gives me a txt file which contains about 50000 points. how i can plot these points in mathematica? thanks
  42. N

    Mathematica Mathematica - Iterations with 2 arguments

    I'm trying to build a simple function that takes 2 arguments. Basically, I want it to do this: x(n+1)=a*sin[x(n)] and generate a list of x0,x1,x2 etc. up to x(n) like NestList does, starting from x0=1.0 So I want to make a list of these iterations, where a is a constant of my choice...
  43. T

    Mathematica Mathematica Real Part of Solve output

    I am trying to solve 0.125 + 0.5 (1-x)^3 - (12.5/y)==0 for x, when y is real and y>0. I thus want to find x= 1- 0.63 ((100-y)/y)^(1/3), so that if y=100, x=1. Mathematica's Solve yields 3 roots: sol=Solve[0.125 + 0.5 (1 - x)^3 - (12.5/y) == 0, x] Root 1: 1.+((0.+0. I) y^(1/3))/(-100.+1...
  44. U

    Mathematica Why Does Mathematica Output Unexpected Results with Derivative Rules?

    Hi! Please help the idiot In[] = D[p[x,t],x,t]/.{Derivative[n_,m_][p_][q__]->a^(n+m)} Out[] = a2 In[] = D[p[x,t],x,t]/.{Derivative[n__][p_][q__]->a^Plus[n]} Out[] = a WTF? Why not a2? In the simplest case In[] = D[p[x,t],x,t]/.{Derivative[n__][p_][q__]->Plus[n]} Out []=Sequence[1, 1] In[]...
  45. N

    Mathematica Problem with numerical solution to Sch eq in Mathematica

    I am trying to solve the potential barrier problem numerically in Mathematica I am giving the following command but it is showing error which i could not figure out a = 2; s = NDSolve[{y1''[x] + k1*y1[x] == 0, y2''[x] + k2*y2[x] == 0, y3''[x] + k1*y3[x] == 0}, {y1[0] == y2[0], y2[a] ==...
  46. C

    Troubleshooting NonlinearModelFit in Mathematica

    Hello, I'm working on this Mathematica assignment, just basic tutorial-type stuff (you can ignore the details about pyrene, not important), and the fit on this function won't converge. Someone in my class said it converged fine, so I was wondering if anyone notices any errors in my work...
  47. ChristinaJ

    Mathematica Mathematica: Module inside For loop

    Hi all, I have the following code which runs without error but gives no output. It's probably simple but I just can't see the problem. LM={}; M[line_, cur_, lq_, ld_, k_] := For [i = 1, Length[line[[1]]], i++, Module[{m}, If[line[[1, i]] == "Q", m = {{Cos[k*Sqrt[Abs[cur]]*lq]...
  48. C

    Mathematica Discrete Fourier Transform of NDsolve in Mathematica?

    I want to do a discrete Fourier transform of the solution I have found using NDSolve, however, because the NDSolve creates Interpolating functions rather than numbers I can't do this. Any help is appreciated. I've attatched the file I'm working with. Catrin
  49. Y

    Mathematica Problem in NDSolve in mathematica

    i want to solve a large system of coupled differential equations but i get this error NDSolve::nlnum: i attach the notebook in zip format. what is the problem? thanks
  50. H

    Mathematica Ordering a list in Mathematica

    Hi everyone, Is it possible to order a list of (x,y) coordinates in Mathematica by x, then y? I currently have a number of data files in which there are 5 columns: x, y, area, circularity, radius. I would like to order the list by x and y coordinates while keeping the rows intact. Thank you
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