At 14:35 07/10/1997 +1000, you wrote:
>Would anyone have an algorithm to do ArcSin of a value.
>Tony

The standard algorithm is a polynomial Tchebichev approximation
which is obtain from an integral form.
Algorithm is finally a sum of (ai.X^n) and with 6 to 8 terms
you will reach a good precision. This is what it is used in
electronic calculator.
To do such calcul you will need:
        - an algorithm to compute X^n
        - an algorithm to convert binary number to "real" number
(exposant + mantissa)
        - an algorithm to compute X*Y with real number
        - another to add real number between themselve.

Unless you wish to spend a lot of time to write such a thing
with a PIC, I think the better is to use 'C' or 'BASIC' or 'PASCAL'
library for PIC.
Another idea would be to use a convertion table with only a few term
(perhaps 64 is enought) and then to compute a function which will
make an interpolation between 2 terms of the table. This will surely
be faster than polynomial approximation, but surely less precize.
The interpolation function will need some mathetical computation in
order to obtain something reliable, depending of researching precizion
perhaps a simple linear interpolation would be enough.

Finally, the algorithm will strongly depend of WHAT you want to do
with ArcSIN function ...

Best regards,
        Philippe TECHER.

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