I am trying to create a function to return lowest fraction value. the sample code is here :
create or replace function fraction_sh(x number) return varchar2
is
fra1 number;
pwr number;
intprt number;
v4 number;
numer number;
denom number;
gcdval number;
frac varchar2(50);
begin
if x <> 0 then
fra1 := mod(x,1);
pwr := length(mod(x,1))-1;
intprt := trunc(x);
numer :=mod(x,1)*power(10,length(mod(x,1))-1);
denom :=power(10,length(mod(x,1))-1);
gcdval := gcdnew(power(10,length(mod(x,1))-1),mod(x,1)*power(10,length(mod(x,1))-1));
if intprt = 0 then
frac := to_char(trunc(numer/gcdval))||'/'||to_char(trunc(denom/gcdval));
DBMS_OUTPUT.put_line(1||' '||denom||' '||gcdval||' '||numer);
else
frac := (intprt*to_char(trunc(denom/gcdval)))+to_char(trunc(numer/gcdval))||'/'||to_char(trunc(denom/gcdval));
DBMS_OUTPUT.put_line(2||' '||denom||' '||gcdval||' '||numer);
end if;
end if;
return frac;
end;
create or replace function gcdnew (a number, b number, p_precision number default null, orig_larger_num number default null) return number is
v_orig_larger_num number := greatest(nvl(orig_larger_num,-1),a,b);
v_precision_level number := p_precision;
begin
if a is null or b is null or (a = 0 and b = 0) then return 1; end if;
if p_precision is null or p_precision <= 0 then
v_precision_level := 4;
end if;
if b is null or b = 0 or (b/v_orig_larger_num <= power(10,-1*v_precision_level) and greatest(a,b) <> v_orig_larger_num) then
return a;
else
return (gcdnew(b,mod(a,b),v_precision_level,v_orig_larger_num));
end if;
end;
Inmost cases it works, but when i try to pass 2/11 it returns 2/10.
Any help appreciated.
The problem with what you're currently doing is precision. With 2/11 the resulting number is 0.1818181... recurring, and the length of that - and therefore the pwr value - end up as 40, which destroys the later calculations.
With modifications to limit the precision (and tidied up a bit, largely to remove repeated calculations when you have handy variables already):
create or replace function fraction_sh(p_float number) return varchar2
is
l_precision pls_integer := 10;
l_int_part pls_integer;
l_frac_part number;
l_power pls_integer;
l_numer number;
l_denom number;
l_gcdval number;
l_result varchar2(99);
begin
if p_float is null or p_float = 0 then
return null;
end if;
l_int_part := trunc(p_float);
l_frac_part := round(mod(p_float, 1), l_precision);
l_power := length(l_frac_part);
l_denom := power(10, l_power);
l_numer := l_frac_part * l_denom;
l_gcdval := gcdnew(l_denom, l_numer, ceil(l_precision/2));
if l_int_part = 0 then
l_result := trunc(l_numer/l_gcdval) ||'/'|| trunc(l_denom/l_gcdval);
else
l_result := l_int_part * (trunc(l_denom/l_gcdval) + trunc(l_numer/l_gcdval))
||'/'|| trunc(l_denom/l_gcdval);
end if;
return l_result;
end;
/
Which gets:
with t(n) as (
select 9/12 from dual
union all select 2/11 from dual
union all select 1/2 from dual
union all select 1/3 from dual
union all select 1/4 from dual
union all select 1/5 from dual
union all select 1/6 from dual
union all select 1/7 from dual
union all select 1/8 from dual
union all select 1/9 from dual
union all select 1/10 from dual
union all select 4/3 from dual
union all select 0 from dual
union all select 1 from dual
)
select n, fraction_sh(n) as fraction
from t;
N FRACTION
---------- ------------------------------
.75 3/4
.181818182 2/11
.5 1/2
.333333333 1/3
.25 1/4
.2 1/5
.166666667 1/6
.142857143 1/7
.125 1/8
.111111111 1/9
.1 1/10
1.33333333 4/3
0
1 1/1
So you might want to add some handling for either passing in 1, or the approximation after rounding ending up as 1/1 - presumably just to return a plain '1' in either case.
I've set l_precision to 10 rather arbitrarily, you can make that larger, but will hit problems at some point so test carefully with whatever value you pick.
(And I haven't looked at gdcnew at all; that can probably be simplified a bit too.)