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Cost of Composition vs Pure Function

• To: mathgroup at smc.vnet.net
• Subject: [mg93646] Cost of Composition vs Pure Function
• From: Raffy <raffy at mac.com>
• Date: Thu, 20 Nov 2008 04:56:01 -0500 (EST)

The speed difference between these two evaluations seems odd,
considering they are effectively the same thing:

m = RandomReal[{0, 1}, {10, 1000, 1000}];

Total[Total[#]]& /@ m; // Timing => 0.14 sec

Composition[Total, Total] /@ m; // Timing => 0.983 sec

Other than the Identity and Inverse Function transformation, where is
this overhead coming from?

Thanks.

• Follow-Ups:
  • Re: Cost of Composition vs Pure Function
    • From: Sseziwa Mukasa <mukasa@jeol.com>