Comments for Jonathan Landrum

Comment on Finding the Difference of Sums using C++ by What Sigma Notation Means to a Computer Scientist :: Jonathan Landrum

What Sigma Notation Means to a Computer Scientist :: Jonathan Landrum — Thu, 23 Feb 2012 04:59:31 +0000

[...] Σ is to sum all i‘s from 1 to 100 (or whatever is on top), as I have shown before when finding sums in c++. An exact analog to a loop. I made a couple corrections to the image from before; I only hope [...]

Comment on Fortran Prime Number Calculator by Calculating the Padovan Sequence with Fortran :: Jonathan Landrum

Calculating the Padovan Sequence with Fortran :: Jonathan Landrum — Thu, 23 Feb 2012 04:57:49 +0000

[...] file and have the function start from the previous number. Or you could even do as I did with my prime number calculator and have the user define a range. As it stands, the program re-calculates every number back to 1 [...]

Comment on Calculating Factorials with a Recursive Function by Calculating the Padovan Sequence with Fortran :: Jonathan Landrum

Calculating the Padovan Sequence with Fortran :: Jonathan Landrum — Thu, 23 Feb 2012 04:56:49 +0000

[...] Because this program uses recursion, caution should be observed when asking for more than 50 or 60 numbers. By putting the general case [...]

Comment on Adding the Even Numbers of the Fibonacci Sequence by Calculating the Padovan Sequence with Fortran :: Jonathan Landrum

Calculating the Padovan Sequence with Fortran :: Jonathan Landrum — Thu, 23 Feb 2012 04:55:00 +0000

[...] Landrum The Padovan Sequence is a recursive series I discovered recently, and it is similar to the Fibonacci Sequence I’ve written about before. The difference is the patterns the two recursive sequences [...]

Comment on Finding the Difference of Sums using C++ by Calculating Factorials with an Iterative Method :: Jonathan Landrum

Calculating Factorials with an Iterative Method :: Jonathan Landrum — Thu, 16 Feb 2012 14:38:07 +0000

[...] if you have an algorithm that gets straight to the answer, choose that one! When I wrote about finding the difference of sums the other day, I skipped all the looping and got straight to the point with Euler’s summation [...]

Comment on Calculating Factorials with a Recursive Function by Calculating Factorials with an Iterative Method :: Jonathan Landrum

Calculating Factorials with an Iterative Method :: Jonathan Landrum — Thu, 16 Feb 2012 14:31:35 +0000

[...] I wrote yesterday about calculating factorials with a recursive function, and I mentioned that there was another method you could use to find the answer [...]

Comment on Adding the Prime Numbers Less Than 2,000,000 by Using Fortran to Calculate the Sum of the Digits of a Very Large Number :: Jonathan Landrum

Sat, 11 Feb 2012 17:43:42 +0000

[...] This number is well outside the limit of integer space, so using a language such as Fortran and returning 2**1000 won’t work. [...]

Comment on Fortran Prime Number Calculator by Computing the nth Prime :: Jonathan Landrum

Computing the nth Prime :: Jonathan Landrum — Mon, 06 Feb 2012 20:49:27 +0000

[...] wrote a program a while back that found all the primes in a list, and it used Fortran to do it. At the time I first wrote this program, one of my instructors [...]

Comment on Collatz Conjecture by paul stadfeld

paul stadfeld — Thu, 02 Feb 2012 04:14:09 +0000

Obviously, no one knows WHY it’s unproven. But take my Mersenne Number example: by the successor rules for forming Mersenne Numbers, one sees that the successor of 1mod3 is 0mod3 and that the sucessor of 0mod3 is 1m0d3 all the way to infinity. Since the first Mersenne Number is 1mod3 with an odd number of bits, that means that all even bit Mersenne Numbers are 0mod3 (and therefore, divisible by 3). What’s important is I don’t HAVE to test every Mersenne Number. This is a simple example. The problem is that no such process has been worked out for Collatz that can decide the issue for the infinite set. So people keep testing it, not because they will ever reach infinity. but on the chance they might stumble on a counterexample. You wouldn’t need to explain why, just demonstrate it.
Also, in Collatz there is something called The Crossover Point. If it’s an interger, then there is a loop cycle. Now before you say “it must never be an integer” consider that when in the negative domain, the rossover Point IS an integer, that’s how we get the loop cycle at -17. As far as I know, there is no positive domain interger Crossover Point, but I can’t prove it. The point is that a mechanism exists that COULD make the conjecture false (although it would be a very large number).

Comment on FizzBuzz by Sum of Threes and Fives :: Jonathan Landrum

Sum of Threes and Fives :: Jonathan Landrum — Wed, 01 Feb 2012 00:07:28 +0000

[...] all integers between 1 and 1,000 that are divisible by either 3 or 5. I immediately thought of the FizzBuzz program I wrote a while back, and realized the algorithm is actually quite similar. It’s just [...]