[BUG] Degrees on CAS
02-25-2014, 10:12 AM
Post: #1
 Tugdual Senior Member Posts: 745 Joined: Dec 2013
[BUG] Degrees on CAS
Context: CAS/Home in degrees

Test 1
Enter cos(90) in CAS just to check you get 0 and are indeed in degrees

Test 2
Enter acos(cos(pi/2)) you get 90
Home returns 1.57 as expected.

Test 3
Enter asin(sin(pi)) you get 0
Home returns 3.14 as expected
02-25-2014, 12:17 PM
Post: #2
 Terje Vallestad Member Posts: 145 Joined: Dec 2013
RE: [BUG] Degrees on CAS
(02-25-2014 10:12 AM)Tugdual Wrote:  Context: CAS/Home in degrees

Test 1
Enter cos(90) in CAS just to check you get 0 and are indeed in degrees

Test 2
Enter acos(cos(pi/2)) you get 90
Home returns 1.57 as expected.

Test 3
Enter asin(sin(pi)) you get 0
Home returns 3.14 as expected

I notice if you remove the tick for Exact in CAS settings, you get the same results as in Home

Cheers, Terje
02-25-2014, 01:23 PM
Post: #3
 Tugdual Senior Member Posts: 745 Joined: Dec 2013
RE: [BUG] Degrees on CAS
Well done Terje. I'll remember you shall not ask the Prime for an Exact result if you want the correct one. Huh what?
02-25-2014, 01:51 PM
Post: #4
 Terje Vallestad Member Posts: 145 Joined: Dec 2013
RE: [BUG] Degrees on CAS
(02-25-2014 01:23 PM)Tugdual Wrote:  Well done Terje. I'll remember you shall not ask the Prime for an Exact result if you want the correct one. Huh what?

Given that "the number π is a mathematical constant that is the ratio of a circle's circumference to its diameter", it may not be too far fetched that the system treats π/2 as 90 in Exact mode?
Maybe others have a clearer understanding/explanation for that?

Cheers, Terje
02-25-2014, 05:56 PM
Post: #5
 parisse Senior Member Posts: 1,053 Joined: Dec 2013
RE: [BUG] Degrees on CAS
Will be fixed with the next release. It was not found before because CAS users generally work in radian. And if you work in degree, there is no reason to enter something like cos(pi).
02-25-2014, 07:32 PM
Post: #6
 Tugdual Senior Member Posts: 745 Joined: Dec 2013
RE: [BUG] Degrees on CAS
(02-25-2014 05:56 PM)parisse Wrote:  Will be fixed with the next release. It was not found before because CAS users generally work in radian. And if you work in degree, there is no reason to enter something like cos(pi).
Except when you test this asin(acos(atan(tan(cos(sin(9)))))
and the result is asin(sin(9)-1/2*pi+90)

pi came on its own, I didn't pull it... and I started suspecting more.
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