I am working with a home-brewed program that evaluates magnetic fields from air-core coils. While I have analytic expressions for the field itself, the code involves numeric integration through regions of the field. It also involves adding up the contributions of several coils.

Speed is becoming an issue. I dearly would like to run some of the integrations (which is where the time is spent) in parallel. The contributions from different coils would trivially parallelize,...

Hi,

I am trying to define a system of units so that I get results in the units I want.

Specifically; I want to use energy in MeV (or eV, if I have to) and masses*c^2 in MeV (or eV) as well. Related, I need ScientificConstants like Planck's h in MeVs etc.

So I say

AddSystem('Accelerator','MeV','meter','second');
UseSystem('Accelerator');

which is accepted. I even get energies converted to MeV if I enter one in a different unit and use

In the Physics package (in Physics:-Vectors, to be more precise), 3-vectors are advantageously represented as

v_:=v1*_i+v2*_j+v3*_k;

with the _i etc. being the unit vectors. I would like to be able to plot these on occasion, either as individual vectors or the line connecting the end points. I can use Component to get at the individual numbers and get this done, but I would like to overload the plot command to do this in a more natural fashion.

By poking...

I ran into an interesting situation with numeric integration.

For a simulation task I need to evaluate an overlap integral of a pair of 3-d ellipsoids which have a certain aspect ratio and the axes of which are tilted against each other. The distribution in each plane is Gaussian, but with largely differing sizes. While I have an analytic expression for the result; the integration (along a certain direction) cannot be done analytically and so I integrate numerically....

One of those vexing things that should be easy:

I am reading in a data file using ImportMatrix. Since the file has one column with texual data I cannot use datatype=float since that bombs. I >can< ImportMatrix with datatype=string or anything.

I then extract columns using the appropriate command and want to do something numeric with them (only with those columns that have correct floating point numbers). That fails since my data are now not floats (even when using anything...