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. F

    Mathematica not plotting for me

    Homework Statement I've been trying to plot Plot[x^2/4 - ln[x]/2, {x, 0, 5}] And it keeps showing me a blank graph. I did it on Wolframalpha and it worked.
  2. Orion1

    Mathematica How Can Mathematica Extract and Reuse Output Values for Further Computations?

    \text{In}[1]:=\text{Solve}\left[\partial _{\theta } \text{Sin}[\theta ]==0,\theta \right] \text{Out}[1]:=\left\{\left\{\theta \to -\frac{\pi }{2}\right\},\left\{\theta \to \frac{\pi }{2}\right\}\right\} Is there a Mathematica source code command that can read a specific numerical value from...
  3. F

    Implicit Differentiation with Mathematica

    Homework Statement I tried using D[x = y - y^2, x, NonConstants -> {y}] and it keeps telling me that y - y^2 is not a valid variable.
  4. F

    Why is Mathematica giving an error when trying to plot xe^{-x}?

    Homework Statement I am trying to plot xe^{-x} by using Plot[x*e^(-x), {x, 0, 5}] and it keeps telling me that Plot::exclul: must be a list of equalities or real-valued functions. So I tried Plot[x*e^(-x), {x, 0, 5}, PlotRange -> {-10, 10}] Still not working The Attempt...
  5. K

    Mathematica How can I fix the warning for solving summation in Mathematica?

    Hi everyone, I have these warning solving summation: ************************************************* In[1]: f[m_, n_] := 2 n + 3 m; In[2]: g[m_, n_] := Sum[f[m, n], {m, 1, m, 2}, {n, n, 1}]; In[3]: g[1, 1] During evaluation of In[3]:= Sum::itraw: Raw object 1 cannot be used as an...
  6. D

    Mathematica Working with the Saha equation in Mathematica

    I am trying to calculate the ionization curve for hydrogen at a given matter density (in this case it happens to be 55 atoms/cm^3) From the Saha equation and putting the concentrations in terms of reaction coordinates. It looks something like this: Log[x[t]^2/(1 - x[t])] = 1/(k t)E - 3/2...
  7. R

    Mathematica Getting mathematica to take more points when it plots

    I've had this problem many times in the past, and haven't thought of a way to fix it. Sometimes when I plot a function that requires quite a bit of effort on mathematica's part, (for example, one time the function was a sum of about a thousand terms, each of which was multiplied complex terms...
  8. R

    Mathematica Mathematica PlotStyle->{color,color,color} not working

    Hi All, running into a bit of a mathematica issue. I put the following code into plot: Plot[Im[correlationList], {t, 0, timeEnd}, PlotStyle -> ColorList] correlationList is a list of complex functions that have been evaluated at t. It correctly plots all of them (if I change it to...
  9. ChristinaJ

    Mathematica Mathematica: Plot time evolution data in 3D

    Hi all, I have 3 lists of data where lists; A={numbers}, B={numbers} and C={{y,m,d,h,m,s},{...}} (i.e. C is in the form DateList). I have no problem plotting using DateListPlot for the 2D case (C VS A) but can't seem to plot all 3 sets of data together. Mathematica seems not to be able...
  10. P

    Global error data set & mathematica cubic spline

    Hey, I have a data set (electronic device output) which we need to find the best fit via approximation and interpolation. I've done a cubic least squares, then found the local error for all the given points (actual - approximate). We need to also find the global errors for the methods we choose...
  11. F

    Plotting Polar Curves in Mathematica: Troubleshooting Homework Statement

    Homework Statement I am trying to plot the two polar curves r = \sqrt{3} cos(\theta) and r = sin(\theta) Mathematica only gives me one of the curves. I tried plotting PolarPlot[{sqrt (3) Cos[t]}, {t, 0, 2 Pi}] and it gives me a blank box in the first quadrant. any ideas?
  12. G

    Mathematica [Mathematica] Combining several Graphics in a Graphics3D

    Hello all, I'll try to make myself clear... My goal here is to plot a function f(x,y) in 3D. But, instead of using the Plot3D[] function, I made a table of Plot[] for, say, several values of the x variable. So I'm now with a list which looks like this ...
  13. M

    Mathematica Extracting frequency from DFT set in Mathematica

    Maybe someone else had this problem. Lets say we have a sampled Gaussian pulse in time domain and transform it into frequency domain. For that I use the discrete Fourier transform. Now the resulting set of transformed values is made up of complex numbers. I want to extract two things from that...
  14. M

    Mathematica Issues with Direct Fourier Transform in Mathematica

    Issues with Discrete Fourier Transform in Mathematica Maybe someone else had this problem. Lets say we have a sampled Gaussian pulse in time domain and transform it into frequency domain. For that I use the discrete Fourier transform. Now the resulting set of transformed values is made up of...
  15. K

    Mathematica What command to be used in Mathematica

    Hi, Iam looking for a specific command(s) that could give outputs which are determinate only, i.e. only and only if the outputs are not infinity. This is due to the fact that I have iterations cases (using Do-loop) which give both determinate and indeterminate outputs. However, I just...
  16. B

    Mathematica Mathematica Spatial 3-D List Plot

    I want to plot a list of points where each element is of the form {x,y,z} so that the list is like: { {x1,y1,z1} , {x2,y2,z2} , ... , {xN,yN,zN} }. And I want to connect a line between each consectutive pair (i.e. {x(i-1),y(i-1),z(i-1)} & {x(i),y(i),z(i)} ). Unfortunately, its not as...
  17. M

    Mathematica Plot 3D matrix as 2D plot and 3rd dimension as color in Mathematica

    Hi! It's been like two days since I have tried to make this work, still I got nothing. Searched Google etc. but no help there. I have a three dimensional matrix in form of {{a,b,c}, {d,e,f}, {g,h,i}, ... etc. } with a total of 51 elements, i.e. 51x3 matrix. What I want is to plot it as...
  18. M

    Mathematica Plotting a family of curves in mathematica

    Hi all, I'd like to plot a family of curves corresponding to different values of an integer n (eg. sin(nx) for n=1,2,3...) on a single graph, along with some kind of indication as to what value of n each curve corresponds to. I'm using the command Plot[Evaluate@Table[Abs[P[-t, n]], {n, 3...
  19. K

    Mathematica Help me to solve Do-loop for large matrices (Mathematica)

    Hi all, I have difficulties about applying the Do-loop command as it takes very long time to run (more than 24 hours and it keeps running). However, if i do it manually, without Do command, i.e. putting the values of the variables, Mathematica gives me a pretty quick output. Please see...
  20. G

    Mathematica Mathematica: solving system of nonlinear equations

    I am trying to solve the following system of 2n variables: w1 + w2 + ... + wn = b0 w1x1 + w2x2 + ... + wnxn = b1 w1x12 + w2x22 + ... + wnxn2 = b2 ... w1x12n-1 + w2x22n-1 + ... + wnxn2n-1 = b2n-1 for w1, w2 ... wn and x1, x2 ... xn. The problem is the using the Solve command returns...
  21. Saladsamurai

    Mathematica Mathematica: How to Do This? (Rules)

    Hi All! I am trying to get used to Mathematica and rules and all things syntax. What I am trying t do is this: If I define a variable as such m = Solve[x^4 - 4 == 0, x] The output is: {{x -> -Sqrt[2]}, {x -> -I Sqrt[2]}, {x -> I Sqrt[2]}, {x -> Sqrt[2]}} So I believe what this means...
  22. A

    Mathematica Solve large equation (Mathematica)

    Hi All, I have a big ugly function (please see the attached Mathematica file), of tau (f(tau)). The only parameters there in symbolic form are w and v. I need to take the derivative of this function with respect to tau, set it equal to zero and solve for tau. (Please see g(tau)). But Solve...
  23. R

    Mathematica Mathematica Plotting Delta Function

    Hi All, I'm trying to plot some DiscreteDelta functions in mathematica but unfortunately since the points are singular nothing shows up in the plot. Usually when this comes up I replace the delta functions with very narrow gaussians, graphically it looks even nicer (I'm plotting absorption...
  24. Z

    Mathematica Solving a Trickier-Than-Usual Circuit Equation with Mathematica 8.0”

    Hello, I'm working on a simple electronic circuit with two resistors and two diodes. I have experimental data of the current-voltage characteristic and am trying to fit the corresponding equation - the resistors and diodes are unknown. With basic circuit analysis, I get this tricky...
  25. K

    Mathematica Random Number Generator (RNG) in Mathematica: Wrapped Cauchy & Von Mises

    I'm trying to use a random number generator in Mathematica that uses a distribution. I know there's a specific command to do so but I'm a bit confused on how to use it. In my example I'm trying to get random numbers from the wrapped Cauchy and Von Mises distributions. Any help would be great...
  26. Saladsamurai

    Mathematica Mathematica: Nested User defined function

    Hello :smile: I am a total amateur here and can't seem to get this to work: I have a function beta[M, θ] that I am trying to define. beta is a nasty equation that is way too many lines for me to input at once, so I tried to break it up into pieces. However, the part that is showing up in red...
  27. K

    Mathematica Need help to solve simultaneous equation in Mathematica

    Hi everyone, please help me to solve my difficulties with regard to simultaneous equations using Mathematica. Thanks for any response.
  28. J

    Mathematica Mathematica - Evaluating a function for different pairs of variables

    I have a function f(x,y) that I wish to evaluate for different values of x and y. I created two lists for x and y using table: x = Table[x,{x,1/10,1,1/10}] y = Table[y,{y,1/100,1/10,1/100}] This gives me 10 values for x and 10 for y. Now I want to evaluate my function f(x,y) for...
  29. M

    Mathematica Get FeynArts and FormCalc for Mathematica 8 - Installation Guide

    Hey I have Mathematica 8 and I'm wondering if FeynArts and FormCalc are already installed or I have to install them from somewhere else? If the first how I can get it? Many thanks in advance
  30. D

    Mathematica Troubleshooting Mathematica Pendulum Equation: Finding Solutions with NDSolve

    I am trying to input the equation of motion for a pendulum: θ1'' = −g (2 m1 + m2) sin θ1 − m2 g sin(θ1 − 2 θ2) − 2 sin(θ1 − θ2) m2 (θ2'2 L2 + θ1'2 L1 cos(θ1 − θ2)) L1 (2 m1 + m2 − m2 cos(2 θ1 − 2 θ2)) with θ2 and θ2'2 being the only unknowns but I am not getting the results that are...
  31. E

    Mathematica Partial derivative of an interpolated function (with Mathematica)

    Hi, I faced a problem (in Mathematica) when trying to plot a partial derivative of a functiona (of two variables) obatined by "Interpolation". More precisely, here is my input: surf=Interpolation[{ {{160.0, 160.0}, 2.852688}, {{160.0, 170.0}, 2.827547}, {{160.0, 180.0}, 2.818931}...
  32. A

    Mathematica How to Rescale the Horizontal Axis in Mathematica?

    Hi All, I have some simple Mathematica commands: f[x_]=x^2+3*x-1 Plot[f[x],{x,0,10}] Now, I need to "rescale" the horizontal axis of the resulting graph, so that number 25 is added to its value (i.e., the horizontal axis would take the starting value 25 (in place of 0) and 35 (in...
  33. R

    Mathematica Mathematica Circular Shift of Array Elements

    Hi All, does anyone know of a mathematica function that efficiently circularly shifts all array elements? e.g. {1,2,3,4,5} -> {4,5,1,2,3} without iterating? The reason I ask is because I have a huge data set I'm working with and right now iterating through is very processing intensive...
  34. A

    Mathematica Fitting Temperature and Experimental Data in Mathematica: How-To Guide

    Hi, I have a question about fitting in Mathematica.I have a function like this: F=T*Y^(0.5) T is temperature but Y obtained from this coupled equation 1-u*Y=u(1-u/Y^.4)^.5*Y I have T and F from experimental data.so I want to obtain u from fitting. could you please advise me how can I do it...
  35. A

    Why is my integration in Mathematica not working?

    Hi, I have a question about fitting in Mathematica.I have a function like this: F=T*Y^(0.5) T is temperature but Y obtained from this coupled equation 1-u*Y=u(1-u/Y^.4)^.5*Y I have T and F from experimental data.so I want to obtain u from fitting. could you please advise me how can I do it...
  36. R

    Mathematica Importing data into mathematica

    I'm having trouble getting data into mathematica. I have a text file will a list with members separated by returns (enters) that I want to import as an array. I tried: Import["data.txt", "Table"] Import["data.dat", "Table"] Import["data.txt"] Import["data.dat"] All of which failed to...
  37. ChristinaJ

    Mathematica Plotting Nested Lists in Mathematica

    All, I am having trouble plotting nested lists. I have two data sets (A and B), both with dimensions 5x50. So far I have plot = Map[ ListPlot[#, PlotRange -> {0, Max[A]}, AxesOrigin -> {0, 0}, Frame -> True, FrameLabel -> {"position", "Intensity"}] &, A]; which...
  38. G

    Mathematica Can anybody help me, who is good with Mathematica, with writing a sequence.

    I am very new with Mathematica and I need help writing a program that generates a Farey Sequence. Farey[n] := ? The result should appear as follows, for those values of N. Farey[1] = {0/1,1/1} Farey[2] = {0/1,1/2,1/1} Farey[3] = {0/1,1/3,1/2,2/3,1/1} Farey[4] =...
  39. ChristinaJ

    Mathematica Import multiple files into Mathematica

    Hi, I'm trying to import multiple files into Mathematica. Each file is a 2d matrix and I would like to import multiple files into a nested list. So far I have something that only allows me to load a single file. In:= SetDirectory["/directory"]; In:= filenames = FileNames[] Out:=...
  40. I

    Mathematica Mathematica Farey Sequence program

    Here is an overview of Farey sequences; http://mathworld.wolfram.com/FareySequence.html" I need to write a program in Mathematica 8, FareySequence[n_], that takes a positive integer n and returns, as a list, the nth Farey sequence. So far I have, Module[{denleft, denright, f, i, j, k...
  41. D

    Seeking help in Mathematica syntax

    Homework Statement I am creating a program to help me analyze a quantum system. I am having a problem creating a large function that I can pass 6 initial values to and get the result out (IT). I am new to this language but have been asked to code in it. Homework Equations I am...
  42. J

    Writing a Farey sequence in Mathematica.

    I need some help writing a Farey Sequence in Mathematica, so far this is all I have: FareySequence[n_] := GCD[a, b]; While b : a, b = b, a % b; result := a Simplify[a, b]; g := GCD[a, b] result := (a/g, b/g) I am very new to programming, please help!
  43. K

    Mathematica Need help problems in Mathematica

    Hi everyone, Please help me to rectify my problem using Mathematica. I got this difficulty on the very last code i.e, solving the simultaneous equation and Do summation process.The remaining codes are all working nicely. As you can see in the attached file, Iam using only variables m = 1...
  44. N

    Fourier Analysis of a sound signal using Mathematica

    Homework Statement I am trying to construct a Mathematica notebook that will be able to import sound in the form of a .wmv file and then create the frequency spectrum for a given time interval. Homework Equations I managed to complete this part, though I am trying to figure out: a)...
  45. J

    I writing a mathematica function.

    The Farey sequence F_n (F subscript n) for any positive integer n is the set of irreducible rational numbers a/b with 0<(or equal to)a<(or equal to)b<(or equal to) n and (a,b)=1 arranged in increasing order. The first one should be: F_1 = {0/1,1/1} F_2 = {0/1,1/2,1/1} F_3 =...
  46. Hepth

    Mathematica Mathematica : Plus Minus Evaluation

    If I have : (1 \[PlusMinus] 5) * 5 I want it to read 5 \[PlusMinus] 25 Does anyone know how to get it to evaluate those? Then get to expand multiple terms with plus minuses in them, and ultimately get a min and max of the value. Such as : (a +- b)(c+-d)/(e+-f) where all...
  47. K

    Mathematica How to convert the root of equation in Mathematica

    Hi all, How to convert the root of an equation from symbolic form into an ordinary from? I have tried to use the N command, but still displaying in the symbolic form. Thanks
  48. P

    Help Interpeting Mathematica Result

    Hi everyone, Given the attached input and result, I'm confused as to how to interpret the 1.1, x.1, and y.1 terms in the solution. Does this mean I'm supposed to dot 1 into 1? How does that work? Any help is appreciated. Of course, x and y are vectors (not that it matters but they're xyz...
  49. S

    Is Downloading UIUC Mathematica Courseware Legal?

    Hello all, Does anyone know anything about copyrighting? I have been downloading courseware 6.0 from math everywhere from the UIUC website (there is a direct download link on the webpage). This is recently become an issue, should I be worried? The material costs money but my school provides...
  50. S

    Mathematica Mathematica: Position of elements in a list

    If I have a list say li = {18, 22, 4, 10} and I want to add for example 7 to this list Join[li, {7}] to get {18, 22, 4, 10, 7}, can I insert the 7 after the 4, to get {18, 22, 4, 7, 10}, I can't just use Sort[ {18, 22, 5, 10, 7}] as I don' t want to change the order of the whole list?
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