The UNIX and Linux Forums awk and trig functions

 Shell Programming and Scripting Post questions about KSH, CSH, SH, BASH, PERL, PHP, SED, AWK and OTHER shell scripts and shell scripting languages here.

# awk and trig functions

## Shell Programming and Scripting

#1
07-03-2009
 pauli Registered User Join Date: Mar 2007 Last Activity: 23 September 2012, 7:52 AM EDT Location: Singapore Posts: 14 Thanks: 0 Thanked 0 Times in 0 Posts
awk and trig functions

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
07-03-2009
 vgersh99   ɹoʇɐɹǝpoɯ Join Date: Feb 2005 Last Activity: 11 December 2013, 9:26 AM EST Location: Foxborough, MA Posts: 7,455 Thanks: 122 Thanked 510 Times in 480 Posts
look here or here or here

Code:
```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) }```

Last edited by vgersh99; 07-03-2009 at 09:47 AM..
#3
07-15-2009
 ubeejani Registered User Join Date: Jul 2009 Last Activity: 15 September 2009, 6:52 AM EDT Posts: 11 Thanks: 0 Thanked 0 Times in 0 Posts
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.
Regards,
Ubee

 More UNIX and Linux Forum Topics You Might Find Helpful Thread Thread Starter Forum Replies Last Post TimHortons Shell Programming and Scripting 2 04-08-2009 11:41 AM amitrajvarma Shell Programming and Scripting 1 11-23-2007 06:52 AM scriptingmani Shell Programming and Scripting 3 07-06-2007 08:15 AM Raom Shell Programming and Scripting 6 07-21-2006 04:06 AM sendhilmani Shell Programming and Scripting 2 03-24-2006 04:40 AM

All times are GMT -4. The time now is 11:43 AM.