Re^2: Monte Carlo - Coin Toss

[jwkrahn]

It is more idiomatic (and often simpler) to use Perl-style rather than C-style loops.

Yes, but it won't work if the numbers are too large for integers and have to use floating point.    Then only C style loops will work.

my @collect = map 0, 0 .. NUM_TOSSES;

Why are you initializing @collect with NUM_TOSSES + 1 elements?

The idiomatic way to initialize @collect with NUM_TOSSES elements is usually:

my @collect = ( 0 ) x NUM_TOSSES;

for ($i = 0; $i < $numTosses+1; $i++) {

foreach my $tailsCt ( 0 .. NUM_TOSSES )

You have an off-by-one error, it should be:

foreach my $tailsCt ( 0 .. NUM_TOSSES - 1 )

Update: oops, I misread the original code.

[johngg]

Why are you initializing @collect with NUM_TOSSES + 1 elements?

The idiomatic way to initialize @collect with NUM_TOSSES elements is usually:

my @collect = ( 0 ) x NUM_TOSSES;

As Eliya points out, 20 tosses could give 21 outcomes as regards the number of "tails" tossed, i.e. 0, 1, ... 19 or 20 so your way should be

my @collect = ( 0 ) x ( NUM_TOSSES + 1 );

and I would agree that your way is perhaps more idiomatic. However, I felt that

my @collect = map 0, 0 .. NUM_TOSSES;

better illustrated the relation between the numbers of tosses and outcomes. What do others think?

[Eliya]

You have an off-by-one error, it should be: ...

No, 0 .. NUM_TOSSES is correct here, because adding up NUM_TOSSES (with a single result being 0 or 1) can potentially produce values ranging from zero to NUM_TOSSES.

Tossing a coin once can produce 0 or 1 tails;
tossing a coin twice can produce 0, 1 or 2 tails;
etc.

[ikegami]

Yes, but it won't work if the numbers are too large for integers and have to use floating point.

If 2 billion loop iterations are not enough for you, you can always nest loops to multiple the range.