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MeBeatYou
Member
Joined: 29 Sep 2005
Posts: 178
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 Posted: 30 Nov 2005 04:15:36 pm Post subject: |
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Thanks for the Linear Regression help, it really did help me out. Instead of wasting another post, I was wondering if there was any way to graph step functions. I thought it would be an interesting thing to try. The calculator comes with a built in function for absolute value (f(x)=|x+2|-3) but not for *forgets exact name* step functions (f(x)=[x])
The brackets symbolize that f(x) has to be equal to the INTEGER less than or equal to X. Is there anyway to graph these 'step functions' on the caluclator?
Click Here For An Example Of A Step Function |
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Weregoose
Authentic INTJ
Super Elite (Last Title)
Joined: 25 Nov 2004
Posts: 3976
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| Posted: 30 Nov 2005 04:28:50 pm Post subject: |
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[font="courier new"]int() is the TI-Basic syntax for the floor() function: [MATH] [[font="courier new"]►] [5]
The floor function is usually represented as  .
You can also use [font="courier new"]round(value,places) or [font="courier new"]iPart().
These are in the very first chapters of the manual.
Last edited by Guest on 01 Dec 2005 02:15:42 am; edited 1 time in total |
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DarkerLine
ceci n'est pas une |
Super Elite (Last Title)
Joined: 04 Nov 2003
Posts: 8328
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| Posted: 30 Nov 2005 06:56:17 pm Post subject: |
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More:
iPart(X) returns the next closest integer to 0 (so if X<0, it will be greater, if X>0, it will be less). Essentially, truncating the decimal part.
int(X) will always return the greatest integer less than or equal to X. Beware, if X is 0.999998 it will still return 0.
To find the least integer greater than or equal to X, use -int(-X).
To round to the closest integer, use round(X,0) or int(.5+X), whichever makes you happier. |
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thornahawk
μολών λαβέ
Active Member
Joined: 27 Mar 2005
Posts: 569
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| Posted: 01 Dec 2005 01:54:09 am Post subject: |
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I split the topic because this isn't very related to regression. Hope you don't mind. :)
Anyway, -int(-X) is functionally equivalent to the so-called "ceiling function" (least integer ≥ X).
Other step functions not explicitly implemented on the calculator are the sign function (X>0)-(X<0) and the unit step function 2(X≥0)-1 (in terms of so-called Iverson brackets).
thornahawk
Last edited by Guest on 01 Dec 2005 01:54:37 am; edited 1 time in total |
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