HP Forums

HP 15c x/16

Program to convert decimal fraction to a fraction readable on a tape measure:

Registers:
STO 0- ORIGINAL NUMBER
STO 1- NUMERATOR
STO 2- DENOMINATOR

Code:

01 LBL A

02 STO 0

03 FRAC      //Creates numerator x as a fraction

             //with 16 as denominator: x/16

04 1         //Use 32 ON steps 04-05 if you want 32nds

05 6

06 STO 2

07 *

08 FIX 0

09 RND

10 FIX 3

11 INT

12 STO 1

13 LBL 7     //Can fraction be reduced?

14 2

15 /

16 FRAC

17 TEST 0     //Same as X#0

18 GTO 8     //If fraction can't be reduced,

             //go to formatting subroutine

19 RCL 2     //Reduce fraction

20 2

21 /

22 STO 2

23 RCL 1

24 2

25 /

26 STO 1

27 GTO 7     //Try again

28 LBL 8     //Formatting subroutine

29 RCL 0     //Original number will be left in y register

30 RCL 1     //The next 7 steps put the fraction

            //into the format Num.Deno:

31 RCL 2     //For Example, 1/16 will display

            //as 1.16, 5/8 as 5.08

32 .

33 0

34 1

35 *

36 +

37 RTN

That's a nice program. Here's a variant that is a little shorter and uses only one register:

Code:

001-42,21,11    LBL A

002-    44 0    STO 0

003-   42 44    FRAC

004-      48    .

005-       5    5

006-      36    ENTER

007-      36    ENTER

008-   43 33    R^

009-       1    1

010-       6    6

011-      20    *

012-      40    +

013-   43 44    INT

014-      48    .

015-       1    1

016-       6    6

017-      40    +

018-42,21, 0    LBL 0

019-      20    *

020-   42 44    FRAC

021-43,30, 7    TEST 7 ; x>y

022-    22 1    GTO 1

023-   43 35    CLx

024-   43 36    LSTx

025-    22 0    GTO 0

026-42,21, 1    LBL 1

027-    45 0    RCL 0

028-   43 36    LSTx

029-      36    ENTER

030-      40    +

031-   43 32    RTN

The numerator and denominator are merged into a single number nn.dd. Thus we can divide both by 2 with a single instruction.
The display settings aren't changed since the function INT(x + 0.5) is used to round a number.
The stack is filled with 0.5 in lines 4-7 because this number can be used often.
Personally I dislike that 16 occurs twice but I couldn't come up with a better solution. Maybe somebody else can?

Kind regards
Thomas

Elegant, Thomas, and a bit faster.

I had a version for the 42S and I ported it quickly to the 15C years ago without much thought. It is a program I used on a daily basis in my work for many years.

Dwight Sturrock

Thomas Klemm

Dwight Sturrock