Thanks Geoff! Bob S
> On Oct 31, 2014, at 21:35 , Geoff Canyon <gcan...@gmail.com> wrote: > > FYI, here's my original bignum multiplier: > > function bigTimes X,Y > if char 1 of X is "-" then > put "-" into leadChar > delete char 1 of X > end if > if char 1 of Y is "-" then > if leadChar is "-" then put empty into leadChar else put "-" into > leadChar > delete char 1 of Y > end if > put (3 + length(X)) div 4 * 4 into XL > put char 1 to XL - length(X) of "000" before X > put (3 + length(Y)) div 4 * 4 into YL > put char 1 to YL - length(y) of "000" before y > repeat with N = XL + YL down to 9 step -4 > repeat with M = max(4,N - YL) to min(XL,N - 4) step 4 > add (char M - 3 to M of X) * (char N - M - 3 to N - M of Y) to S > end repeat > put char -4 to -1 of S before R > delete char -4 to -1 of S > end repeat > if S is 0 then put empty into S > return leadChar & S & R > end bigTimes > > > > On Fri, Oct 31, 2014 at 11:32 PM, Geoff Canyon <gcan...@gmail.com> wrote: > >> I've created similar routines in the past. Are you saying you do or don't >> want to allow for arbitrarily-large divisors? >> >> a pseudo-code algo for divisors that LC can handle: >> >> 1. remove the decimal points, remembering where they were >> 2. get the length of the divisor >> 3. grab that many characters from the dividend as the working dividend >> 4. if the working dividend is larger than the divisor, divide it by the >> divisor to find the quotient and remainder (new working dividend) and put >> the quotient after the final quotient >> 5. put the next character from the dividend after the working dividend and >> return to (4) until you run out of dividend >> 6. figure out where the decimal point goes and insert it >> >> for divisors that LC can't handle, (4) becomes: >> >> 4. if the working dividend is larger than the divisor, use your bignum >> subtraction to repeatedly subtract the divisor from the working dividend to >> find the quotient and remainder (new working dividend) and put the quotient >> after the final quotient >> >> >> On Thu, Oct 30, 2014 at 7:51 PM, Igor de Oliveira Couto < >> i...@semperuna.com> wrote: >> >>> Hi all, >>> >>> I wanted to develop a library to allow me to perform basic maths (add, >>> subtract, multiply, divide) with arbitrarily long numbers in LiveCode. My >>> requirements are simple: >>> >>> - integers and floating-point numbers must be supported as all operands >>> in all operations, to an arbitrarily large number of decimal cases >>> >>> - speed is NOT an issue: performances can safely be relatively slow, as >>> it is unlikely that it’ll need to perform hundreds of thousands of >>> operations per second >>> >>> - accuracy IS an issue: needless to say, all operations must provide >>> *accurate* and *reliable* results, regardless of how many decimal cases are >>> used >>> >>> It proved relatively easy to do the addition, multiplication and >>> subtraction operations in LiveCode. I followed the ‘pen-and-paper’ >>> algorithm, and it all seems to be working really well - I’m happy to >>> provide anybody with a copy of the scripts off-list, if you wish (just send >>> me an email directly). I’m stuck, however, trying to implement DIVISION. >>> There does not seem to be an “easy” pen-and-paper algorithm that would >>> support arbitrarily large numbers with unknown number of decimal cases. >>> >>> Most long-division algorithm seems to expect that the number being >>> divided can be of an arbitrarily length, but they expect that the divisor >>> (the number we are dividing BY) is going to be low enough, so that the >>> person making the division will “know” instinctively how many times it >>> would “fit” into the number being divided. These algorithms are not >>> recommended once we start dealing with divisor of 3 digits or more. There >>> does not seem to be an algorithm that would allow us to procede >>> “digit-by-digit” with the division, as can be done with >>> addition/subtraction/multiplication… Or is there? >>> >>> Searching Google and Wikipedia has yielded articles about using bitwise >>> operations, or complex mathematical theory, both of which are beyond me. Is >>> there a Math Wiz in this list, who could give us a layman’s explantion of >>> an algorithm that could be used? Any help would be much appreciated! >>> >>> Kindest regards to all, >>> >>> -- >>> Igor Couto >>> Sydney, Australia >>> >>> _______________________________________________ >>> use-livecode mailing list >>> use-livecode@lists.runrev.com >>> Please visit this url to subscribe, unsubscribe and manage your >>> subscription preferences: >>> http://lists.runrev.com/mailman/listinfo/use-livecode >> >> >> > _______________________________________________ > use-livecode mailing list > use-livecode@lists.runrev.com > Please visit this url to subscribe, unsubscribe and manage your subscription > preferences: > http://lists.runrev.com/mailman/listinfo/use-livecode _______________________________________________ use-livecode mailing list use-livecode@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-livecode
