Math Forum / Math Software / Mathematica / April 2008

HellO Szabolcs,
I liked your surface so much, I thought I might share this fun Manipulate:
sphere[ls_] := Function[{x, y, z}, x^2 + y^2 + z^2 < ls^2]
Manipulate[

What is the syntax of opening a package:
<<"c:\path\package.m"
Is the path able to be added so the package may be accessed.

I am considering running my research project on a computer cluster on
campus. However, the computer cluster requires the programs to be in C++,
and I've already coded much of the project in Mathematica. Do converters
such as MathCode C++

I'm running Mathematica 6.0.2 on a MacPro with 8 cores. I've noticed
that the kernel only uses 1 core=85 Is it possible to enable multicore
calculations ?
Thanks in advance :)

Suppose that we want to take the third element of every sublist from the
following list:
lst = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}}
One way to do this is to use lst[[All, 3]]

Apparently Arrows is only a 2D graphic. Is there a way to make an arrow
in 3D?
Robert M Lurie

I have a notebook related question. I have about 50
notebooks open on the screen with different titles. I
want to select the notebooks with certain titles. I do
have this working:

I am trying to solve this Common Multiple Value Question based on 2
sequences of values...
This is both a Math question & also a question on how to apply this problem
to Mathematica.

v=[1 2 3];a=ones(v)
the result is:
a(:,:,1) =
    1     1

Is there a simple way to crop a surface to a sphere?
For example, consider the surface
ContourPlot3D[
  -x^4*y^2 + x^2*y^4 + x^4*z^2 - y^4*z^2 -

I am trying to find the number of eigenvalue crossings for a matrix as
a function of the parameter 'u', on which the elements of the
(symmetric) matrix depend on linearly. The matrix elements also
involve randomly chosen constants. The plan is to find the

In Mathematica, how can I change integral variables? For example in
integration:
Integrate[Sin[Sqrt[x]], x] if I want to use t^2=x to instead x in the
integral, how can I achieve this?

Dear Mathgroup,
I am trying to integrate the pdf of a chi-square mixture distribution.
If I define the pdf as
pdf2[0] := .25

are there examples to plot such chart ?
http://www.wolfram.com/solutions/finance/images/fibonarcs.gif
(the picture is from here: http://www.wolfram.com/solutions/finance/features.html
)

((1*12 + 4)*11 + 4)*10 + 4
1804
I need help with a function find the Calander "base"
Cbase[1804,{12,11,10}]