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Genel • Gezegen

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by badfish99 (826052) on Friday March 30, @02:16PM (#18546613)

As a mathematician, I'm always surprised by people who think that 4 and 4.0 should not be equal.

by zappepcs (820751) on Friday March 30, @02:21PM (#18546729)

As a mathematician, I'm always surprised by people who think that 4 and 4.0 should not be equal.

Well, one is just a number, the other is the SP version identifier that tells you when its safe to upgrade to a new version of windows.

by rootofevil (188401) on Friday March 30, @02:22PM (#18546733)

As a programmer, I'm always surprised by mathematicians who think that 4 and 4.0 should be equal.

by IMarvinTPA (104941) on Friday March 30, @02:33PM (#18546921)

As a programmer, I'm amused by both.

4 and 4.0 are equal by value but not in precision. 4 has one significant digit, while 4.0 has two. This is important because multiplying it by 1200 (which has two significant digits), yields two scientifically different answers. 4*1200 yields 5000 (5 x 10^3) while 4.0*1200 yields 4800 (4.8 x 10^3).

So, in the end, it depends, just like everything else.
by zippthorne (748122) on Friday March 30, @02:56PM (#18547315)

As an engineer, I'm also amused.

4.0 is definitely a 2 sig dig number, but 4 could be 1 sig dig or it could be "exact." You wouldn't say the 2 in 2*pi*r is only one significant digit, would you? Of course not, it would render any precision in pi or r meaningless.

Also, 1200 could have 2, 4, or be exact depending on the context. It's best to always use a notation that includes the fraction mark for non-exact quantities.
 

by twistedsymphony (956982) on Friday March 30, @03:51PM (#18548161)

Heh, thank you. As an engineer I was also going to make this point, I'm glad I'm not the only one who realizes that the number of 0s after a decimal carries with it some hefty implications in the manufacturing and engineering realm. Working for a bearing manufacturer I can tell you that the difference between a part with a diameter of 4.00cm and a part with a diameter of 4.00000cm is a few hundred dollars.