Wolfram Mathematica

### Possible Bug in LinearSolveFunction with Sparse Vectors

Bug introduced in 5.0 and fixed in 11.0 LinearSolveFunction is new in 5.0 Consider the following set of equations and corresponding variables: eqns1 ={2 x == 2 - 4 y, 3 y == 4 z, 2 z + 4 t == 3, 3 t + 2 z == 5}; vars .... Brooklyn: 7 hours ago

Wolfram Mathematica

### The fastest way of raising indices of high rank tensor

I have some high dimensional high rank tensors, let's say \$\$F_{ijkl}\$\$ and I need to find \$\$F^{abcd}=g^{ai}g^{bj}g^{ck}g^{dl}F_{ijkl}.\$\$ Here \$g^{ij}\$ is the contravariant metric. Simple summation in Mathematica takes way to much time Do]=Sum]g]g]g]g],{i,1,dim},{j,1,dim},{k,1,dim},{l,1,dim}],{a,1,dim},{b,1,dim},{c,1,dim},{d,1,dim}] But I can sum over first and last index using matrix multiplication, so first I calculate \$F^a{}_{ij}{}^d\$ .... Leo: 7 hours ago

Wolfram Mathematica

### InputField as both in- and output fields with ContinuousAction

Many years ago, I made a handy little program in Flash. It consisted of a number of input fields, each representing a variable that was dependent on all the others. As soon as any field changed, the other followed, no matter which of them I changed. So they where effectively .... Nolan: 7 hours ago

Wolfram Mathematica

### Maximizing a function with assumptions

Using f := Log/s When I run the following line: Assuming,s]] I get the following output: Maximize/s, s] Actually, Mathematica ignores the assumptions and outputs the function only. That is, nothing is done by Mathematica. I know that Assuming works with Refine, Simplify, and Integrate. But, is there any way .... Carson: 8 hours ago

Wolfram Mathematica

### How can I find different areas of triangles from a list of points?

If I have a list of points such as {{1, 1}, {4, 7}, {24, 67}, ..., {17, 83}}, how can I find the area of triangles formed by different combinations of these points? For example, what code would I need to find the area of the triangle formed by {{1, .... Hailey: 8 hours ago

Wolfram Mathematica

### How to use Through by default on numeric functions?

I've used the following code to simulate defining operations between functions: ThroughFunctions := expr//.{ x_?NumericQ -> x, (f_/;MemberQ, NumericFunction]) :> Through] } \$Pre = ThroughFunctions; Since it's assigned to \$Pre the substitution occurs without having to wrap the expressions in the function ThroughFunctions: In:=(Cos^2/(3+Sin)) Out=Cos^2/(3+Sin) The problem with this is .... Penelope: 9 hours ago

Wolfram Mathematica

### Labeling points with numbers in a Graphics expression

Can I label points with numbers in my Graphics expression, as in this picture Here is my code. Off {α, γ, ω} = {0.1, 0.05, 1}; T = (2 π)/ω; a = NDSolve - γ (1 - x^2) x' + x == α Cos, x == 0, x' == 0}, .... Jade: 11 hours ago

Wolfram Mathematica

### Eliminate 3 Variable from 4 Equations

I am trying to use Mathematica to Eliminate 3 following variable from 4 equations. Any clue or link to similar solved problem is highly appreciated: eq = { Cos + Cos + Cos == a, Sin + Sin + Sin == b, Cos + Cos + Cos == c, Sin .... Nora: 11 hours ago

Wolfram Mathematica

### How to find and verify relationships between functions?

MMa gave me a complicated result involving Hypergeometric0F1's. It was much less complicated after I discovered this identity: Hypergeometric0F1 = BesselJ 1) Is there a way to get MMa to validate relationships between functions, for example if I wasn't sure the identity above was true? FullSimplify - BesselJ] does return .... Miles: 12 hours ago

Wolfram Mathematica

### NMaximize - global maximum fail - How to?

Problem : Let x,y,z be non-negative real number whose sum is 1. Find maximum of 0.2x + 0.2y + x^2*z + y*z^2 What I did first was reducing variable. 0.2x + 0.2y + x^2(1-x-y) + y(1-x-y)^2 with constraint x>=0, y>=0, x+y<=1 Mathematica code is NMaximize and I got {0.226147,{x->0.,y->0.455858}} But .... Leilani: 12 hours ago