Maintenance script: Initial automated import

2016-02-24T18:06:11Z

Initial automated import

New page

{{Template:TI-BASIC:Command
|picture=FPART.GIF
|summary=Returns the fractional part of a value.
|syntax=fPart(''value'')
|location=Press:
# MATH to access the [[TI-BASIC:Math|Math]] menu.
# RIGHT to access the NUM submenu.
# 4 to select fPart(, or use arrows.
|compatibility=TI-83/84/+/SE
|size=1 byte
}}

fPart(''value'') returns the fractional part of ''value''. Also works on complex numbers, lists and matrices.

fPart(5.32)
.32
fPart(4/5)
.8
fPart(‾5.32)
‾.32
fPart(‾4/5)
‾.8

= Advanced Uses =

fPart(, along with [[TI-BASIC:Int|Int(]] or [[TI-BASIC:Ipart|IPart(]], can be used for integer [[TI-BASIC:Compression|Compression]].

------

Also, fPart( is an easy way to find A mod B (the positive remainder when A is divided by B).

:B(A<0)+iPart(BfPart(A/B))

If A is guaranteed to be positive, the following shorter code can be used, omitting B(A<0):

:iPart(BfPart(A/B))

------

Finally, the easiest way to check if a number is a whole number is not(fPart(X:

:If not(fPart(X:Then
: // X is an integer
:Else
: // X is not an integer
:End

You can use this, for example, to check if a number is divisible by another: if X is divisible by N, then X/N is a whole number. This is useful when you want to find the [[TI-BASIC:Factorization|factors]] of a number. Warning: when storing values with repeating decimals and later multiplying them to see if a number makes it an integer it can return a value of 1 or -1 instead of 0 even if it is an integer. Example: if you store 1/3 as X and then do fpart(3x) it will return 1 instead of 0. This is because fpart(.999...) results in .999... and then rounds to 1 when displaying rather than rounding to 1.0 and then displaying the fpart( as 0.

= Optimization =

Often you want to find the value of a-1 mod b -- this occurs, for example, in movement routines with wraparound. However, the problem is that if a=0, a-1 will be negative. Rather than use the longer version of the modulo routine, you might replace subtracting 1 with adding (b-1). This will have the same result, but without sign problems.

= Related Commands =

* [[TI-BASIC:Int|Int(]]
* [[TI-BASIC:Ipart|IPart(]]
* [[TI-BASIC:Round|Round(]]

= See Also =

* [[TI-BASIC:Compression|Compression]]
* [[TI-BASIC:Factorization|Number Factorization]][[Category:TI-BASIC]]
[[Category:TIBD]]

TI-BASIC:Fpart - Revision history

Maintenance script: Initial automated import