Talk:Roots of unity

I think the Seed7 output has its real and imaginary parts reversed. (1.000*i)² is -1 not 1. --Mwn3d 07:14, 21 January 2008 (MST)

Seed7 uses a similar convention as Algol68: The i is the separator between real and imaginary part (well in Algol68 it seems to be an i with an underscore which IIRC is a different alphabet). The output of -0.5000i+0.8660 means -0.5000+i*0.8660 which might be counter intuitive. I choosed it that way to make the 'parse' function (which converts a string to a complex) easy implementable as:

(**
 *  Return the conversion of a string to a complex.
 *)
const func complex: (attr complex) parse (in string: stri) is func
  result
    var complex: result is complex.value;
  local
    var integer: iPos is 0;
  begin
    iPos := pos(stri, 'i'); # Find the position of the i
    if iPos <> 0 then
      result.re := float parse (stri[.. pred(iPos)]);
      result.im := float parse (stri[succ(iPos) ..]);
    else
      raise RANGE_ERROR;
    end if;
  end func;

Maybe you have suggestions of how the output of a complex number should look like. If I write a complex number as -0.5000+i*0.8660 the 'parse' function could be:

(**
 *  Return the conversion of a string to a complex.
 *)
const func complex: (attr complex) parse (in string: stri) is func
  result
    var complex: result is complex.value;
  local
    var integer: iPos is 0;
  begin
    iPos := pos(stri, 'i'); # Find the position of the i
    if iPos > 1 then
      result.re := float parse (stri[.. iPos - 2]);
      result.im := float parse (stri[iPos + 2 ..]);
      if stri[pred(iPos)] = '-' then
        result.im := -result.im;
      elsif stri[pred(iPos)] <> '-' then
        raise RANGE_ERROR;
      end if;
      if stri[succ(iPos) len 1] <> "*" then
        raise RANGE_ERROR;
      end if;
    else
      raise RANGE_ERROR;
    end if;
  end func;

What do you think? Thomas Mertes 09:35, 21 January 2008 (MST)

Whatever is easier is fine as long as other people can figure it out. Maybe the output should explained a bit in the example. --Mwn3d 09:52, 21 January 2008 (MST)