calculating inductance

From:  Kevin Wahila [SMTP:wawa-at-spectra-dot-net]
Sent:  Friday, January 23, 1998 10:55 AM
To:  tesla-at-pupman-dot-com
Subject:  calculating inductance

i used to have a bookmark for a web page that would allow you to enter
parameters to calculate the inductance of various shapes.  does anyone have
this link?  i am specifically looking for a formula for a toroid.  i also
remember something about the permitivity (i think that was the word) of the
substance.  what is the permitivity of ferrite?