awk and trig functions

Shell Programming and Scripting
1

dear all,

In my script, it would be ideal if I could use an arc-cos (inverse cos) function. I think trig functions are indeed provided by awk, but not inverse trig functions.

So my question simply is: are there any alternative ways to incorporate inverse trig functions into a script?

Any help greatly appreciated!

Many thanks,

pauli

2

look here or here or here

function asin(x) { return atan2(x, sqrt(1-x*x)) }
function acos(x) { return atan2(sqrt(1-x*x), x) }
function atan(x) { return atan2(x,1) }
3

Hello,
I want to calculate distance between two GPS coordinates(Latitude A, Longitude A, Latitude B, Longitude B). By Spherical Law, the formula is:
distance= ACOS ( SIN(latA) * SIN(latB) + COS(latA) * COS(latB) * COS(longB-LongA)) * R
where R= Radius of the earth(6371)
As there is no ACOS function in awk, therefore I have to use the following method:
function acos(x) { return atan2(sqrt(1-x*x), x) }
value = sin(latA) * sin(latB) + cos(latA) * cos(latB) * cos(longB-LongA)
distance = acos(value)*R
But I don't know when I calculate the distance using this method, I get different value from Spherical law formula. For Spherical Law I use MS Excel to calculate the value.
I need your help please.Thanks a lot.
Regards,
Ubee