Opened 12 years ago
Last modified 8 years ago
#2697 new enhancement
Calculate should use an appropriate number of significant figures for trigonometric functions
Reported by: | greenfeld | Owned by: | rwh |
---|---|---|---|
Priority: | Unspecified by Maintainer | Milestone: | Unspecified |
Component: | Calculate | Version: | 0.92.x |
Severity: | Minor | Keywords: | |
Cc: | walter, lucyd | Distribution/OS: | OLPC |
Bug Status: | New |
Description
Calculate should use an appropriate number of significant figures for trigonometric functions. Right now it provides errors in the noise where it should provide a zero answer.
This potentially could confuse students if none of their other figures are that minuscule. Seen in Calculate-36 in OLPC 11.2.0 os13.
Examples seen on an XO-1.5 (using degrees; radians are similar):
- sin(180) = 1.22460*10^{-16}
- cos(90) = 6.12303*10^{-17}
- tan(90) = 1.63317*10^{16} {technically I believe this is undefined, but Google's calculator makes the same mistake for this one entry}.
Change History (5)
comment:1 Changed 11 years ago by godiard
comment:2 Changed 10 years ago by lucyd
I propose the following idea for solving this issue.
- Maintain a window of digits in the current computed value after decimal point
- Check if any non-zero digit(significant figure) occurs in this window
- If yes then go with the current format
- If no then approximate the value to zero
This approach is for values between 0 and 1. Similarly we can check in a window of digits before the decimal point for approximating the value to infinity. All other cases follow the existing format.
comment:3 Changed 10 years ago by godiard
- Cc walter added
comment:4 Changed 10 years ago by lucyd
- Cc lucyd added
comment:5 Changed 8 years ago by vikramahuja1001
Will be automatically solved after solving #4814
This ticket can be related to #2332