Hey, now. I know that some of us are newbies to python, but that doesn't mean that we're all newbies to math concepts. (Even advanced ones.) Having said that, I will shut my fat mouth now because it will be my luck that the math is beyond what I can handle. I wouldn't mind seeing the code. Even if it is long, I wouldn't mind seeing it. A private message is acceptable for something too lengthy for the tutor list.
Jacob > Hi Matt, > > > Ok. I have to admit that my mathematical maturity is actually a little > low, but I'll try to follow along. But this really doesn't sounds like a > problem specific to Python though, but more of a math problem. > > So you may actually want to talk with folks with a real math background; I > would not be mathematically mature enough to know if your code is correct. > I'd strongly recommend talking to folks on the 'sci.math' or > 'sci.math.num-analysis' newsgroups. > > > I haven't seen your code, so I'm still in the dark about how it works or > what its capabilities are. I'll make a few assumptions that might not be > right, but I have to start somewhere. *grin* > > Does your code provide a way at getting at all possible solutions, or only > one particular solution? If so, then you can just filter out for > solutions that satisfy the property you want. > > For example, we can produce a function that generates all squares in the > world: > > ### > >>> import itertools > >>> def allSquares(): > ... for i in itertools.count(): > ... yield i*i > ... > >>> squares = allSquares() > >>> squares.next() > 0 > >>> squares.next() > 1 > >>> squares.next() > 4 > >>> squares.next() > 9 > >>> squares.next() > 16 > >>> squares.next() > 25 > ### > > > I can keep calling 'next()' on my 'squares' iteration, and keep getting > squares. Even though this can produce an infinite sequence of answers, we > can still apply a filter on this sequence, and pick out the ones that are > "palindromic" in terms of their digits: > > ### > >>> def palindromic(n): > ... "Returns true if n is 'palindromic'." > ... return str(n) == str(n)[::-1] > ... > >>> filteredSquares = itertools.ifilter(palindromic, allSquares()) > >>> filteredSquares.next() > 0 > >>> filteredSquares.next() > 1 > >>> filteredSquares.next() > 4 > >>> filteredSquares.next() > 9 > >>> filteredSquares.next() > 121 > >>> filteredSquares.next() > 484 > >>> filteredSquares.next() > 676 > ### > > > This sequence-filtering approach takes advantage of Python's ability to > work on a iteration of answers. If your program can be written to produce > an infinite stream of answers, and if a solution set with all positive > coefficients is inevitable in that stream, then you can take this > filtering approach, and just capture the first solution that matches your > constraints. > > > > Similarly, if your program only produces a single solution, does it do so > through an "iterative" algorithm? By iterative, I mean: does it start off > with an initial guess and apply a process to improve that guess until the > solution is satisfactory? > > For others on the Tutor list, here is an "iterative" way to produce the > square root of a number: > > ### > def mysqrt(x): > guess = 1.0 ## initial guess > while not goodEnough(guess, x): > guess = improve(guess, x) > return guess > > def improve(guess, x): > """Improves the guess of the square root of x.""" > return average(guess, x / guess) > > def average(x, y): > return (x + y) / 2.0 > > def goodEnough(guess, x): > """Returns true if guess is close enough to the square root of x.""" > return abs(guess**2 - x) < 0.00001 > ### > > (adapted/ripped off from material in SICP: > http://mitpress.mit.edu/sicp/full-text/book/book-Z-H-10.html#%_sec_1.1.7) > > > > If your program tries to solve the problem through an iterative process, > then, again, does it inevitably produce a solution where all the constant > coefficients 'Cn' are positive? If so, maybe you can just continue to > produce better and better solutions until its satisfactory, until all the > coefficients are positive. > > > Otherwise, without looking at your code, I'm stuck. *grin* And even if I > do see your code, I might be stuck still. If your code is short, feel > free to post it up, and we'll see how far we can get. But you really may > want to talk with someone who has a stronger math background. > > Good luck to you! > > _______________________________________________ > Tutor maillist - [EMAIL PROTECTED] > http://mail.python.org/mailman/listinfo/tutor > _______________________________________________ Tutor maillist - [EMAIL PROTECTED] http://mail.python.org/mailman/listinfo/tutor
