IDL is a very powerful computer graphics package.

The work that I will be doing will involve creating huge 3d arrays of data.

We can think of this as making a cube, and dividing it up into thousands (or millions) of smaller cubes,

and into each of these smaller cubes we place a data value.

I have an IDL program that looks at this cube of data and can pick out all those locations that have a certain value in common.

The routine is called "Iso-surface".

The program is interactive. It prompts the user to enter the value at which they require an iso-surface to be created. Here's the program code.

I have a fortran program that solves the 3d heat equation.

I ran this program in such a way as to create 3 data sets: one for each component of my vector.

Here's the IDL output of my results for the first component, with the isosurface level chosen to be 0.5.