Expressing Decimals as Fractions

[The]

Is there a way in QBasic to express a decimal answer (x) as a fraction? So instead of printing .25, it would print 1/4? Thanks

 

[The]

Or, if there isn't a way to do that, is there a way to check if x is a decimal? (yes, I am a newbie)

 

[qbasicking]

The only way I could think ouf would be:

IF x <> INT(x) THEN 'check to see if its a decimal
FOR top = 1 TO 500000
FOR btm = 1 TO 500000
IF top / btm = x THEN GOTO prnt
NEXT
NEXT
END IF
prnt: PRINT STR$(top) + &quot;/&quot; + STR$(btm)

This would be incredibly slow though, i would just leave it as a decimal

 

[Pappy1942]

Hi,
Using STR$, MID$, INSRT, and VAL you can convert the number to a string, extract the decimal part, convert it back to a whole number and figure out the denominator. The denominator will alwasy be a power of ten. For instance .101 is equal to 101/1000.
Hope this gives you a clue.
BTW you have to reduce to get 1/4 from .25 (25/100).
Pappy
You learn new something everyday.

 

[logiclrd]

I wrote a program a long time ago that estimates a decimal value using an integer fraction. It works on the following principle: if you invert the fraction, then you are left with an expression of the form 1/x, where x is the *inverse* of the fraction. Furthermore, if you take away the integer part of the fraction, then you are left with another fraction to compensate for, so x is of the form (a + y), where a is the integer part and y is the compensation for the fractional part. You can then repeat with 'y' and end up with an expression of the form:
[tt]
0 + 1
-------------------
5 + 1
-------------
2 + 1
-----
...
[/tt]
(for the fraction 0.18723 -- this approximation yields 0.1875 after 4 levels, the above fraction simplifying to 3/16). This nested fraction is easy to convert back to a simple fraction: you simply start with the deepest nesting, incorporate the integer part into the fraction, then &quot;invert and multiply&quot; to do the division. The result is one less level with the same structure.

Here is the program itself:
[tt]
DIM intPart%(20)
fraction# = .1835718238#
levels% = 10
FOR i% = 1 TO levels%
compensation%(i%) = INT(fraction# + .00001#)
IF ABS(intPart%(i%) - fraction#) < .00001 THEN
levels% = i%
EXIT FOR
END IF
fraction# = 1# / (fraction# - intPart%(i%))
NEXT i%

numerator& = intPart%(levels%)
denominator& = 1&

FOR i% = levels% - 1 TO 1 STEP -1
temp& = numerator&
numerator& = intPart%(i%) * numerator& + denominator&
denominator& = temp&
NEXT i%

dashes& = INT(LOG(denominator&) / LOG(10)) + 4
format$ = RIGHT$(SPACE$(17) + STRING$(dashes&, &quot;-&quot, 17) + &quot; = #.############&quot;

PRINT USING &quot; ###,###,###,###&quot;; numerator&
PRINT USING format$; CDBL(numerator&) / denominator&
PRINT USING &quot; ###,###,###,###&quot;; denominator&
[/tt]