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. Hepth

    Mathematica MATHEMATICA : Forcing Logarithms to Simplify

    How can I force : A Log[b] + A Log[c] to simplify to A Log[b c]? I tried, A,b,c all elements of reals, but it doesn't do it. (Assume everything is Real) I know I can make some patterned rules but I'd rather have it be by default. (i.e. : a_ Log[b_] + a_ Log[c_] :> a Log[b c])
  2. H

    Mathematica MATHEMATICA: NDSolve, 2nd order ODE, Table of IC HELP

    Hi all, I have a 2nd order ODE I am trying to solve using NDSolve. In the ODE there are two constant coefficients and an initial condition that I want to 'vary'; meaning, I have a table of initial conditions with corresponding constant coefficients. It is straight forward to solve the ODE...
  3. G

    Mathematica How can I find fixed points for a map with a range of r values?

    Hello , i wanted to ask sth I have a map : xn+1=rxne-xn , r>0 and r<20 I want to find fixed points .My problem is that i don't have a value or r.I can't manipulate the r values. (if i had an r value i would do : r=2;) My code is: y[x_]:= r x Exp[-x]; To find the fixed points ...
  4. M

    Mathematica Where Can I Find Good Mathematica Programming Tutorials and Books?

    Hi everybody, This is my first post in this forum. So, "Hello everybody" ! I hope someone can help me. I started to learn Mathematica a few weeks back and really like the software. I actually prefer it over Matlab but that's just my personal opinion. I used 'Mathematica demystified' and...
  5. A

    Mathematica How Can I Compute the Saturation of Each Element in a Matrix Using Mathematica?

    I have three n x n matrices for which I am try to compute the saturation of each element in the matrix. The function to find this is S:=1-3(Min r,g,b) where r,g,b are the color channel matrices. For my output I am trying to get it to return an n x n matrix with each element having the function S...
  6. I

    Mathematica Logarithmic 3D plot in Mathematica

    Hi all, Does anyone know how to get Mathematica make a 3D plot with logarithmic axes? I need a, say, 3D version of LogLogPlot. I have a 3D function Rdb[nf, pf] which I want to plot for {nf, 10^10,10^18} and {pf, 10^10,10^18}. I can get cross sections of what I need when I do...
  7. Y

    Plotting a line with negative slope in Mathematica

    I want to plot a line in mathematica with a negative slope by setting it's starting point, length, and slope but i couldn't figure out how to do it. example: A line "AB" has a starting point (40,0) has a length 10 has an angle 127 degrees between x axisIn MATLAB i can do this with %% k =...
  8. R

    Mathematica Misaddressed letters problem with mathematica

    Hi I'm trying to solve this famous problem with Mathematica: "How many ways can a math professor incorrectly address Christmas cards so that no card gets to the originally intended recipient" I found a recurrence formula but don`t know how to implement it in Mathematica, this is the...
  9. D

    Mathematica Really Introductory Mathematica Question

    Hello everyone, I apologize for posting such an introductory mathematica question, but I can't find an answer anywhere. I seem to be having trouble assigning variables and then plotting with the variable name. Perhaps I'm thinking too much in terms of ordinary computer programming or...
  10. T

    Finite Difference Approximation, Mathematica code

    Homework Statement I have to program a three component decay chain using finite difference approximation. I understand finite difference and have written my code, but I have an error I can not find which is giving me an erroneous answer. The curve is correct, but the magnitude of the...
  11. G

    Mathematica Learn Arithmetic & Geometric Progression Formulas with Mathematica 5.0

    Hi to everyone I'm new to this forum and if someone knows about formulas or how to generate the arithmetic and progression geometric and with the software Mathematica 5.0?! Both of these have starting member and step for calculation...Thanks in advance, G.S
  12. Telemachus

    Mathematica Mathematica, Plot3D command and 3D points

    Hi there. Well, I got a surface plotted with Mathematica. I've used the Plot3D command for this. But now I want to plot a point in the same graph. The thing is I've used Taylors polynomial of second degree, and I want to "see" the point around which I'm making the approximation. But I don't know...
  13. G

    Mathematica How do I fit damped harmonic motion data (x vs. t) using Mathematica?

    How do I fit the data given below into the standard form (ignore the part saying to use MathCad): http://screensnapr.com/u/apmqkd.png {{{0.002, 0.726}, {0.022, 0.739}, {0.042, 0.75}, {0.062, 0.759}, {0.082, 0.768}, {0.102, 0.776}, {0.121, 0.785}, {0.141, 0.794}, {0.161, 0.802}...
  14. Hepth

    Mathematica Mathematica - Show timing in output line

    While I know there exists: In[1]:= Timing[Integrate[blah]] Out[1]:= {result,time it took to calculate} Is there a way to just have the time it took to process a step appear in the Out[1]:= part, or after every step rather than having to use the Timing function and then pull out the...
  15. O

    Mathematica Mathematica -difference of two Symbolic summations

    I wish to compute Sum[f[i], {i, 0, m}] - Sum[f[i], {i, 0, j}] but can't get the expected result Sum[f[i], {i, j+1, m}] I also tried Sum[f[i], {i, 0, m}] - f[0] but can't get the expected result Sum[f[i], {i, 1, m}] It seems that mathematica can't change the minimum/maximum...
  16. S

    Mathematica [mathematica]- problem with the output

    Hi everyone, i have a problem with mathematica. I am supposed to compute the eigenvalue of a matrix, and I need the expression for the eigenvalues analytically. But it output strange symbols. and I am unable to decipher what it means. What I got is an output consisting of words like root and...
  17. H

    Mathematica Mathematica: plot and evaluate function of 2 variables

    Hi all, I am trying to evaluate and plot a function of two variable in mathematica. Function: R(t,\theta) = a(t) + b(t)*Y_n(\theta) Where a(t) and b(t) are functions (that I have evaluated already), and Y is the spherical harmonic for a given n, and R is the radius. In...
  18. G

    Calculating Multiple Integrals on Mathematica (Electric fields)

    I'm trying to calculate several stuff about the electric field generated by 2 "plaques" My main problem being that in mathematica it calculates fast for a point of the electric field generated in the Y component, but if i try to make the median of all the points in the plaque it takes way to...
  19. A

    Mathematica Mathematica vs gnuplot vs matplotlib (efficency)

    Hi, I'm currently working on a C program where I have a huge 2d array that changes with time, so in the end, what I have is a 3d array (double 25*24000*100) in a plain text file (about 700MB). I tried to import with Mathematica7 as a "Table" but after a long time (about 15 minutes) the kernel...
  20. H

    Mathematica Mathematica: 2nd order PDE, variable coefficients

    a\text{''}[t]+B[t]*a'[t]-A[t]*a[t]==0 a[0] = 10^-9 a'[0] = 0 a[t] = ? The coefficients A and B are variable over time. I HAVE solved (experimental and theoretical values) for the values of A and B over the time interval of interest! I attempted to solve for a[t] using NDSolve as one...
  21. H

    Mathematica: 2nd order PDE variable coefficients

    a\text{''}[t]+B[t]*a'[t]-A[t]*a[t]==0 a[0] = 10^-9 a'[0] = 0 a[t] = ? The coefficients A and B are variable over time. I HAVE solved (experimental and theoretical values) for the values of A and B over the time interval of interest! I attempted to solve for a[t] using NDSolve as one...
  22. N

    Plot Polynomial Q10[x] with Variables x & t, Range 0-1

    I want to plot this polynomial: Q10[x_] := c* (1 - (t - x)^2)^10 I defined variable 't' in f(t) and 'x' in the polynomial Q10[x]. how can I plot this polynomials with variebles x and t? the range-interval will be (for both x and t): [0,1]. can you write the code please... Thanks... Edit...
  23. H

    Mathematica Mathematica: Animated plot sphere as function of time

    Hi all, Kinda new to Mathematica. I have evaluated a function describing a sphere's (or just circle for simplicity) radius over time. I have made a Table of values for the radius over a given time interval, and am able to plot the radius vs time. How can I make an animated 3D plot of...
  24. O

    Mathematica Changing x-axis in Mathematica

    Hi guys I am trying to plot a function with respect to T, but I want to rescale my axis. For example my range right now shows 0, 10, 20, 30. But I want it to show 0, 1, 2, 3 and so that I can then put an x-axis label of T/10. Can anyone help?
  25. A

    Mathematica Anyone using Mathematica on Unbuntu

    Just wonder if anyone in our little community is using Mathematica on Linux or Unbuntu. I have another license to use and a box with Unbuntu.
  26. G

    Mathematica [Mathematica] Ordered matrix multiplication

    Hello everyone, I have a list, let's call it L1, of length N. Each element of this list is a square matrix. I would like to : 1/ Apply MatrixExp[] to each element of L1 (I know how to do that) 2/ Multiply each element of the subsequent list _in an ordred fashion_ i.e. from element N to...
  27. U

    Help with Mathematica Code: Matching Two Lists

    Hi guys, I am writing a code for mathematica... I have two lists for t(time) and T(temperature) such that t=(t1,t2,t3...tn) and T=(T1,T2,T3,T4,T5...Tn) I have a formula that needs me to correspond the values in the two lists...which means... T1 is the value recorded at t1... any...
  28. D

    Mathematica Mathematica - automatically change function name in for loop

    Hi folks, i just want to call different functions which are solutions of set of rate equations from s= NDSolve in a loop to calculate something. For[k = 0, k < 27, k++, x[k] = N#[time] /. s; ] # is just an arbitrary sign. i just want to replace # with k so i call N0[time]...
  29. radou

    Mathematica Solve Linear Function from Set of n Points with Mathematica

    OK, here's a problem I'm trying to solve for my work. Given a set of n points {(x1, y1), (x2, y2), ... (xn, yn)} I need to obtain a linear function f from the broken line which connects all these points, so that I can the value of f at any point. I need to do this for two sets of points, i.e...
  30. F

    Mathematica Numerical solution in Mathematica

    Hello, I have a problem with numerical solution of the system of ODE's (geodesic eqs.) in Mathematica. The only relevant command I have found is NDSolve. It works perfectly, unless my equations contain functions which are again computed using numerical methods. Simple example illustrating...
  31. Y

    Mathematica Optimizing parameters without specifying them (Mathematica)

    I use NMinimize to optimize a likelihood function. The number of parameters included depends on the dimensions of a vector I pass. I would like to have Mathematica check the dimensions of the vector, declare the correct number of parameters for me, and then solve for them. Right now, I have...
  32. Rasalhague

    Mathematica Calculate Derivative of Function in Mathematica

    Mathematica: In[1]:= x = {(u + 2 v)/3, (u - v)/3, w}; D[x[u], u] Out[1]= {1/3, 1/3, 0}[u] + {(u + 2 v)/3, (u - v)/3, w}’[u] Why does it do this? Wolfram Alpha gives the answer I expected...
  33. J

    Mathematica Produce a bifurcation diagram using mathematica

    I want to produce a bifurcation diagram using mathematica to represent equilibrium points of p1 using the data obtained from the following code, where pn1, pn2, pn3 are recrusion exquations. i.e. x-axis will be the paramter t (ranging from 0-0.3) and y-axis will be the values of p1 this code...
  34. W

    Mathematica Difficult implicit function in mathematica.

    Hi everybody. I have an impicit function that I want to solve numerically in mathematica it looks like: f[x] == b1 \!\( \*SubsuperscriptBox[\(\[Integral]\), \(0\), \(L\)]\(c[ x, \[Alpha]] f[\[Alpha]] SuperscriptBox[\(E\), \(-\( \*SubsuperscriptBox[\(\[Integral]\), \(0\)...
  35. J

    Mathematica and Variation of Parameters

    Hi, I was solving the following second order ODE: http://www.texify.com/img/%5CLARGE%5C%21x%5E2%20y%5E%27%27-5xy%5E%27%2B5y%3Dx%5E6%20sinx.gif I used variation of parameters and found this solution...
  36. A

    Help with Mathematica: Graph Period vs Theta Not

    Homework Statement Graph in Mathematica to solve d^2theta/dt^2 + g/lsin(theta)= 0 Show a graph of period vs. Theta not. Homework Equations The Attempt at a Solution I am not very experienced with entering information into mathematica. I am aware that the manipulate plot...
  37. A

    Pendulums, total energy?, and Mathematica

    Homework Statement A)Show that for a non-frictional, simple linear pendulum (Sin(theta) ~ theta) the total energy of the pendulum (K + U) or kinetic plus potential is given by E = (1/2) m l^2 (d(theta)/dt)^2 + (1/2) mgl (theta)^2 and therefor E = (1/2) mgl(theta0)^2 theta0 =...
  38. J

    Mathematica [TetrahedralGraph] - mathematica

    Using the following code in mathematica: << DiscreteMath`Combinatorica` ShowGraph[TetrahedralGraph] Produces a regular Tetrahedral Graph. I would like to show data points on this tetrahedral graph with specific coordinates relating to the four points of the tetrahedron. Is this...
  39. T

    Mathematica Mathematica- Rotating a 2D plot into a 3D plot

    I have a plot of radius and temperature. I want to plot it in 3D by rotating it about the origin to produce a 3D plot. I can not figure out how to do this in Mathematica without doing it by hand and then plugging it into the Plot3D function. Any advice would be greatly appreciated. The...
  40. Y

    Mathematica Mathematica: dealing with significant figures

    Hi everyone. Hopefully this is easy to solve. I have large amounts of mined data that have differing levels of precision. I want to do analysis of: 1) number of decimal places present 2) significant figure error intervals based on the precision (for instance, 0.003 could have been...
  41. A

    Mathematica Mastering Differential Equations in Mathematica: A Complete Guide

    What is Mathematica command for differential equation y''+2y'+5y=(sinx)*(e^x)?
  42. J

    Mathematica Making a Tetrahedron in Mathematica

    I want to make a tetrahedron in mathematica. For example, suppose: {a = 0.2, b = 0.5, c = 0.1, d = 0.3} {a = 0.1, b = 0.2, c = 0.4, d = 0.3} {a = 0.4, b = 0.3, c = 0.2, d = 0.1} {a = 0.6, b = 0.2, c = 0.1, d = 0.1} and I want a tetrahedrom so that the four points are a, b, c and d -...
  43. S

    Mathematica Mathematica - Constructing Matrices

    Good day to all, I am stuck with this. I am trying to construct a matrices with this properties... if n = 8, suppose the matrix with size 1 by 8 become [16 -16 16 -16 16 -16 16 -16] if n the matrix become [2n -2n 2n -2n 2n -2n 2n -2n ] with size 1 by n I do appreciate if someone...
  44. S

    Mathematica Mathematica NMinimize Program Running Slow - What's Wrong?

    i try run my program for NMinimize.it took a long time to solve.What is the problem of my coding?
  45. Y

    Mathematica Declaring/filling arrays of arbitrary size in Mathematica

    edit: Forgot to add Mathematica in the title. Sorry! Hi everyone. I mined a lot of data and want to analyze it in Mathematica. The data is of the form {{x11, y11, x12, y11, x13, y13},{x21, y21, x22, y22}...} meaning that each set of x,y pairs is not necessarily the same size...
  46. F

    Mathematica Technical problem with Mathematica

    Hello, my name is Maciek, and I come write from Poland. I have big problem with Mathematica. The Program does not work. I can not put the coursor in a notebook, can not do any calculatins. Uninstall and install did not help. Mayby someone of You had simillar problem. Thank You for help!
  47. Y

    Mathematica Precision issues in Mathematica (i think)

    Hi everyone. It's my first time posting in here. I have a mathematica notebook that defines a four-parameter prob density function (PDF). I define a likelihood function, import some data, and run a Nelder-Mead optimization strategy on the likelihood function using the data. My likelihood...
  48. E

    Recognize a product of two vars in Mathematica?

    I am wondering if anyone can tell me how to get Mathematica to recognize the product of two variables so that I can do things like take limits. For example, if I had a function F[x] = x*(R*W)^2 + 4*x and I want Mathematica to take the limit as (R*W)->0, how can this be done? I realize this...
  49. W

    Mathematica Mathematica Animation for power point?

    Is there a way to animate and export a 3D plot such that it rotates about the z axis automatically? A friend is doing a presentation and I'd like to make some animated files of the 3D plots we've been making to include in a power-point. I've looked through help files and some google searches...
  50. K

    Mathematica Mathematica for Poincaré sections - or maybe a different tool?

    Hi, I have a system of ODE's for which I want to compute points for a Poincaré section. I used NDSolve and EventHandler in Mathematica but EventHandler appears rather messy/limited for my condition: Suppose I want to save 4 iterations of a Poincaré map and then abort integration imediately...
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