Re: Using "/@" Effectively
- To: mathgroup at smc.vnet.net
- Subject: [mg104310] Re: Using "/@" Effectively
- From: "Sjoerd C. de Vries" <sjoerd.c.devries at gmail.com>
- Date: Tue, 27 Oct 2009 04:58:43 -0500 (EST)
- References: <hc38lq$iae$1@smc.vnet.net>
You need to use Apply here instead of Map. To be precise, you need
Apply on level 1 for which @@@ is the shorthand notation. So you would
write:
Sound[melody[#1, #2] & @@@ {{0, 1}, {5, 0.5}, {7, 0.5}, {12, 1}}, {0,
3}, SoundVolume -> .5]
Actually, melody @@@ works as good as melody[#1, #2] & @@@ .
Additionally, melody[p_Integer, d_Real] needs to rewritten as
melody[p_Integer, d_?NumberQ] so that d can be both reals and
integers.
BTW In your examples you should try higher midi values to hear
anything, or you should have a very good sound card. On my PC I need
at least more than 50.
Cheers -- Sjoerd
On Oct 26, 6:30 am, BenT <brt... at pdmusic.org> wrote:
> Given:
>
> $Version
> "7.0 for Microsoft Windows (32-bit) (January 30, 2009)"
>
> miditofreq[n_Integer] := (440./64) 2^((n + 3)/12);
>
> and
>
> melody[p_Integer, d_Real] :=
> Play[Sin[miditofreq[p] 2 \[Pi] t], {t, 0, d}, SampleRate -> 44100,
> SampleDepth -> 16]
>
> I want to be able to use a list of pitch and duration values for a
> melody, and use it like the following, but cannot determine the method
> to Map them properly, as in this (non-working) attempt:
>
> Sound[melody[#1, #2] & /@ {{0, 1}, {5, 0.5}, {7, 0.5}, {12, 1}}, {0,
> 3}, SoundVolume -> .5]
>
> Can anyone show me the correct (or even a better) way to do so?