Timeline for Computer algebra errors
Current License: CC BY-SA 2.5
5 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jun 11, 2010 at 17:23 | comment | added | Kevin O'Bryant | Very peculiar. So N[x] does its work with certain precision, while N[x,k] does its work aiming for a certain precision. I've been using Mathematica a long time, and never realized this. | |
| Jun 10, 2010 at 15:37 | comment | added | Wilberd van der Kallen | Indeed N[x - Round[x], MachinePrecision] returns -480.\\ But N[x - Round[x], \$MachinePrecision] returns -7.499274028018143*10^-13\\ The decision to make N[x - Round[x], MachinePrecision] mean N[x - Round[x]] is indeed a bad one. | |
| Jun 10, 2010 at 14:19 | comment | added | Kevin O'Bryant | The documentation for "N" states: `N[expr,n] attempts to give a result with $n$-digit precision. N[expr,n] may internally do computations to more than $n$ digits of precision.' Both N[x-Round[x],15] and N[x-Round[x],16] give the right answers, while N[x-Round[x],$MachinePrecision] gives "-480.", and $MachinePrecision itself returns "15.9546". | |
| Jun 10, 2010 at 8:42 | comment | added | Wilberd van der Kallen | You do not understand. The first three should not be 16-digit. They should do the computation in 16 digit. That is something very different. | |
| Jun 10, 2010 at 1:12 | history | answered | Kevin O'Bryant | CC BY-SA 2.5 |