News for hackers. Stuff that matters.

A comment on The case of the 500-mile email.

Re:The case of the 500-mile email by miles on Monday April 26, 2010 @05:06AM (#1294450)
If you're running OS X, it pays to grab gunits http://gunits.darwinports.com/

Here's why:

  $ units
  500 units, 54 prefixes

  $ gunits
  2411 units, 71 prefixes, 33 nonlinear units
[ Parent | on HN ]
Re:The case of the 500-mile email by ianferrel on Monday April 26, 2010 @02:27PM (#1295496)
Can you provide an example of a nonlinear unit?
[ Parent | on HN ]
Re:The case of the 500-mile email by moxiemk1 on Monday April 26, 2010 @03:07PM (#1295627)
They mean that the conversion is defined by a function rather than a scaling factor.

The example that the manual gives is Centigrade to Fahrenheit, which, interestingly enough, is a linear function. http://www.gnu.org/software/units/manual/units.html#Nonlinea...

[ Parent | on HN ]
Re:The case of the 500-mile email by lmkg on Monday April 26, 2010 @03:51PM (#1295769)
It depends on your definition of linear. In some algebra contexts you would call it a linear function because it's a line, but in linear algebra you would not consider it a linear transformation because it doesn't pass through the origin[1]. It would be more accurate to call it "affine."

[1] More generally, being "linear" means that f(ax+y) = af(x) + f(y) for constant a and variables x, y. From this, it follows that f(0) = 0 for linear transformations.

[ Parent | on HN ]