[erlang-questions] Erlang/YAWS vs Free Pascal/Xitami

[Ulf Wiger]

It would seem as if the cost of the chosen math operations is not
that crucial for overall performance.

The Erlang code is obviously much more compact.
It can be made more compact by noting that:

  somma(L) -> somma(L,0).
  somma([], Acc) -> Acc;
  somma([H|T], Acc) -> somma(T, Acc+H).

is equivalent to lists:sum(L)

  quadrati([H|T]) -> [(H*H)|quadrati(T)];
  quadrati([]) -> [].

is equivalent to [X*X || X <- L]

  diff([H|T], K) -> [(H-K)|diff(T,K)];
  diff([], _) -> [].

is equivalent to [X-K || X <- L]

...which gives us:

var_dev(V) ->
  Len = length(V),
  Media = lists:sum(V) / Len,
  D = [X-Media || X <- V],
  Q = [X*X || X <-D],
  S = lists:sum(Q),
  Var = S / Len,
  Dev = math:sqrt(Var),
  {Media, D, Q, S, Var, Dev}.

out(A) ->
Z=lists:seq(1,1000),
{Media, D, Q, S, Var, Dev} = var_dev(Z),
T=io_lib:format("Std Dev: ~.6f ", [Dev]),
{html, T}.



BR,
Ulf W


2008/3/25, Jilani Khaldi <jilani@REDACTED>:
> Which is better for my web application?
>  http://www.dotpas.org/cgi-bin/articles/a01
>
>
>  --
>  ***
>  Jilani KHALDI
>  http://www.dotpas.org
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