Incorrect values with some trigonometric functions - Printable Version +- HP Forums ( https://www.hpmuseum.org/forum)+-- Forum: HP Calculators (and very old HP Computers) ( /forum-3.html)+--- Forum: HP Prime ( /forum-5.html)+--- Thread: Incorrect values with some trigonometric functions ( /thread-11169.html) |

Incorrect values with some trigonometric functions - jeanjpersia - 08-03-2018 10:43 PM
I don't have too much time with this my HP prime rev:C and in an exam, I realized that when I try to put things like Cos(π/2) the answer is not the number that I want, I have a similar problem with graphics if I put the cursor in (1,0) the calculator says that I have in (0.99999999,0). If someone knows what I need to change in settings to solve the problem, it would be great. thanks in advance! Here an example: https://imgur.com/649PMSj RE: Incorrect values with some trigonometric functions - Aries - 08-04-2018 06:52 AM
I think you need to go to CAS mode to get the correct result and set the angle measure to radians in the Home Settings Best, Aries RE: Incorrect values with some trigonometric functions - Stevetuc - 08-04-2018 07:28 AM
(08-04-2018 06:52 AM)Aries Wrote: I think you need to go to CAS mode to get the correct result and set the angle measure to radians in the Home Settings The small error will still exist in home mode though. It exists in the Casio too but the casio rounds such residual errors in trig functions to 0 to present a clean result. The Prime is more honest. Maybe for educational use, there could be a user flag that toggles this behaviour so that say a trig result below a threshold < 1e-11 say, is displayed as 0. RE: Incorrect values with some trigonometric functions - Aries - 08-04-2018 09:26 AM
(08-04-2018 07:28 AM)Stevetuc Wrote:(08-04-2018 06:52 AM)Aries Wrote: I think you need to go to CAS mode to get the correct result and set the angle measure to radians in the Home Settings Y' know, Home = numerical and CAS = symbolic, on any numerical calculator getting a non-zero result (for cos(pi/2)) is an acceptable solution, as PI cannot be represented numerically. This is where CAS comes into play, as a symbolic solver. As you said, the Prime is more honest in this respect. Best, Aries RE: Incorrect values with some trigonometric functions - Stevetuc - 08-04-2018 10:39 AM
(08-04-2018 09:26 AM)Aries Wrote:(08-04-2018 07:28 AM)Stevetuc Wrote: The small error will still exist in home mode though. It exists in the Casio too but the casio rounds such residual errors in trig functions to 0 to present a clean result. The Prime is more honest. Maybe for educational use, there could be a user flag that toggles this behaviour so that say a trig result below a threshold < 1e-11 say, is displayed as 0. Indeed. I was targeting home mode in my comments. Any calc not showing an error here (numeric mode) is truncating or rounding the error. Im happy to see the error, but I can understand the comforting feeling to see cos(pi/2)=0, which is why the casio presents it as such even for a numeric calculation! RE: Incorrect values with some trigonometric functions - jeanjpersia - 08-04-2018 01:42 PM
(08-04-2018 06:52 AM)Aries Wrote: I think you need to go to CAS mode to get the correct result and set the angle measure to radians in the Home Settings THANKS!! RE: Incorrect values with some trigonometric functions - Aries - 08-04-2018 06:30 PM
(08-04-2018 01:42 PM)jeanjpersia Wrote: My pleasure Best, Aries RE: Incorrect values with some trigonometric functions - Tim Wessman - 08-05-2018 03:04 AM
Also note that you can quickly toggle your angle settings by tapping near the clock, and then on the appropriate angle symbol. |