Sep
12
Ooptimus Find Me Not (please)
Supercalifragilisticexpialidocious
What is in a name?
Sep
2
My new brush pen.
I’m currently reading 14 books, at the same time. Well, a few pages in each book during the week. I’m glad I got all those bookmarks from my local bookstore for free.
Aug
26
Triangular numbers without for loop
This Programming in Objective-C 2.0 book wanted me to calculate triangular numbers with the following code:
int n, triangularNumber;
triangularNumber = 0;
for ( n - 1; n <= 200; n = n + 1)
triangularNumber += n;
Really? According to me,
T(n) = 1 + 2 + 3 + … + n
T(n+1) = 1 + 2 + 3 + … + n + (n + 1)
T(n+1) - T(n) = (n + 1) … [1]
The average value of a term in T(n) is the half the sum of the term with the biggest value and the term with the smallest value. This average term is added n times. Or:
T(n) = 0.5 * n * (n + 1) … [2]
T(n+1) = 0.5 * (n + 1) * ((n+1) + 1)
= 0.5 * (n + 1) * (n + 2)
= 0.5 * n * (n + 1) + 0.5 * 2 * (n + 1)
T(n+1) - T(n) = (n + 1) … [3]
Since [1] is the same as [3], [2] must be correct. This would give the following code to replace the earlier code:
int n, triangularNumber;
n = 200;
triangularNumber = n * (n + 1) / 2;
That seems much more efficient than using a for loop.
Aug
21
“Damn it, Bones, you’re a doctor. You know that pain and guilt can’t be taken away with a wave of a magic wand. They’re the things we carry with us, the things that make us who we are. If we lose them, we lose ourselves. I don’t want my pain taken away! I need my pain!”
Captain James Tiberius Kirk in Star Trek V, The Final Frontier
Jul
29
Headache sucks! It really does.
Jul
26
I still doubt the usefulness of Twitter.
Jul
24
Where’s that pack of smokes when you need it?
Jul
20
Reached zero tumblarity! Lower, please!
My goal is to become the least read person blogging on Tumblr, who still add posts on a regular basis. Secretly I’m hoping for sub-zero figures. Can you help me?
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