Converting Binary numbers to Decimal using decimal numbers

[BigBear]

Turing:

fcn tobinary (num1 : string) : real     %Converts a decimal number to a binary number     var whole : string := ""     var remainder : string := ""     var Whole : int     var Remainder : real     var position : int     for i : 1 .. length (num1)         if num1 (i) = "." then             position := i         end if     end for     for i : 1 .. length (num1)         if i < position then             whole += num1 (i)         elsif i >= position then             remainder += num1 (i)         end if     end for     Whole := strint (whole)     Remainder := strreal (remainder)     var temp : int     var binary : string     var num := Whole     var intPower : int := 0     var decimal : int := 0     loop         temp := num mod 2         if temp = 1 then             decimal := decimal + (10 ** intPower)         end if         intPower := intPower + 1         num := num div 2         exit when num = 0     end loop     binary := intstr (decimal)     if Whole < 0 then         binary := "-" + binary     end if     var decimalremainder : real := Remainder     var decimalremainder1 : real     var tempdecimal : string := ""     var check : string     var count : int := 0     var del : real     var remainder1 : string := "0"     loop         decimalremainder1 := decimalremainder * 2         if decimalremainder1 >= 1 then             tempdecimal += "1"         else             tempdecimal += "0"         end if         check := realstr (decimalremainder1, 1)         for i : 1 .. length (check)             if num1 (i) = "." then                 position := i             end if         end for         for i : position .. length (check)             remainder1 := check (i)         end for         del := strreal (remainder1)         count += 1         exit when del <= 0.10 or count = 14     end loop     var reorder : string := "."     for decreasing i : length (tempdecimal) .. 1         reorder += tempdecimal (i)     end for     var finally := strreal (binary) + strreal (reorder)     result finally end tobinary put tobinary ("5.5")

I am trying to convert a decimal number with a decimal portion into a binary number with a decimal portion. I have added a lot of variables to try to break it down and get it to work. I have a seperate function for binary to decimal but the decimal portion is different.

[Tony]

This doesn't look like IEEE 754

[BigBear]

No it doesn't.....

[Tony]

So what kind of format are you going for here?

[BigBear]

What do you mean by format?

[Tony]

How do you want the output to look? What is 5.5 supposed to look like, in binary?

[BigBear]

I guess the 5.5 is right. But 5.4 doesn't work and it should be

101.01100110011001

Because exit when count = 14 but that could be changed to four or something.

[Tony]

ok, I see the 5. => 101.

but how are you going from .4 to .01100110011001 ?

[BigBear]

you take the decimal portion of the number .4 and times it by 2 and the whole number portion is either a 1 or 0 so

Turing:

decimalremainder1 := decimalremainder * 2         if decimalremainder1 >= 1 then             tempdecimal += "1"         else             tempdecimal += "0"         end if

then it checks the decimal portion of that new number and sees if it is less than .10 which it will not be because it has a repeating decimal portion of 0110

So it will iterate 14 times (as it sits) so the wholenumber portion will be added to

tempdecimal then it will be added to the 101 part

[Tony]

so, if I understand...

0.4 * 2 = 0.8 -- record 0
0.8 * 2 = 1.6 -- record decimal 1 as binary 1 ?

So the natural question then... how do you convert back to decimal?

[BigBear]

But this function doesn't work

For decimal you can find how long the decimal portion is and start at a - number and do the div and mod way

[[Gandalf]]

wtd's Number Bases Article on the CompSci.ca Wiki.

[BigBear]

[quote="[Gandalf] @ Mon Apr 06, 2009 6:39 pm"]wtd's Number Bases Article on the CompSci.ca Wiki.[/quote]

Yeah I understand the number systems but I am trying to find something wrong with my function I thibk it is a little thing

[Insectoid]

That's the way I use, and the way Dan was taught in 2nd year uni. I still haven't figured out how to convert back, as you are discarding numbers.

[BigBear]

insectoid @ Mon Apr 06, 2009 7:36 pm wrote:

That's the way I use, and the way Dan was taught in 2nd year uni. I still haven't figured out how to convert back, as you are discarding numbers.

I have finished the function to convert from binary to decimal if that's what you meant by convert back