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sin/cos with awk

 
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# 1  
Old 06-18-2011
sin/cos with awk
I am trying to use awk to find the trigonometric functions (in degrees) I found this on:
Trigonometric functions - Rosetta Code

Code:
print "  sin(-30) =", sin(-30 * degrees)

which says it has an output of:

Code:
sin(-30) = -0.5




But when I use it I get the wrong answer:
Code:
awk '{print "  sin(-30) =", sin(-30 * degrees)}' One.txt

Code:
sin(-30) = -0

I tried more than one value they are all wrong... any idea why?

SmilieSmilieSmilie
Last edited by radoulov; 06-18-2011 at 05:53 PM.. Reason: Code tags!
# 2  
Old 06-18-2011
Your variable "degrees" is undefined and for awk it is equivalent 0. So sin(-30*0) = sin(0) = 0. What is really strange why it is equal -0.
# 3  
Old 06-18-2011
What does your One.txt file contain ?

You should specify in radian instead of degree :
Code:
[ctsgnb@shell ~/sand]$ awk 'BEGIN{print sin((atan2(0, -1))/2)}'
1
[ctsgnb@shell ~/sand]$ awk 'BEGIN{print sin(-(atan2(0, -1))/2)}'
-1
[ctsgnb@shell ~/sand]$ awk 'BEGIN{print cos((atan2(0, -1))/4)}'
0.707107
[ctsgnb@shell ~/sand]$ awk 'BEGIN{print sin((atan2(0, -1))/4)}'
0.707107

since
atan2(0, -1) produce π

You could have a look at this link

Code:
awk 'BEGIN{print "sin(-30 degree)="sin(-30*atan2(0,-1)/180)}'
sin(-30 degree)=-0.5

Last edited by ctsgnb; 06-18-2011 at 09:24 AM..
 
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