hello
I want to make sure that using atan function.
I have two maps containing sin and cosine values in radian.
Using atan function in r.mapcalc is correct in this way:
r.mapcalc dene='atan(map_cosine*180/3.14,map_sine*180/3.14)' ?
kind regards
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Ahmet Temiz
General Directory of Disaster Affairs
Ankara TURKEY
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temiz wrote:
I want to make sure that using atan function.
I have two maps containing sin and cosine values in radian.
sine and cosine aren't angles, so they aren't "in radians" (or
anything else).
Using atan function in r.mapcalc is correct in this way:
r.mapcalc dene='atan(map_cosine*180/3.14,map_sine*180/3.14)' ?
If you want the result in degrees:
r.mapcalc 'dene=atan(map_cosine,map_sine)'
For radians:
r.mapcalc 'dene=atan(map_cosine,map_sine)*3.14/180'
There is no point scaling the sine/cosine values, although it won't
make any difference as atan(y*k,x*k) == atan(y,x) for all k > 0.
[Aside: does r.mapcalc need a pi() function? Or deg2rad()/rad2deg()
functions? Or, for that matter, anything else?]
--
Glynn Clements <glynn.clements@virgin.net>
On Tue, Nov 04, 2003 at 12:26:50PM +0000, Glynn Clements wrote:
[...]
[Aside: does r.mapcalc need a pi() function? Or deg2rad()/rad2deg()
functions? Or, for that matter, anything else?]
Yes, that would be nice. So we all had the same pi, and the
other proposed functions were also convenient.
Markus