RE: Product

*To*: mathgroup at smc.vnet.net*Subject*: [mg87527] RE: [mg87457] Product*From*: "Jose Luis Gomez" <jose.luis.gomez at itesm.mx>*Date*: Sat, 12 Apr 2008 06:59:06 -0400 (EDT)*References*: <200804110542.BAA04653@smc.vnet.net>

(* Steven *) (* I think it is an interesting question *) (* See what happens when we compare total with other ways to add many small integers *) (* First a test list:*) In[1]:= mytestlist = Table[RandomInteger[{1, 9}], {1000000}]; (* add all the numbers in the list, and also report the computer time used to calculate:*) In[2]:= Timing[Plus @@ mytestlist] Out[2]= {0.266, 5003966} (* AGAIN add all the numbers in the list, BUT THIS TIME USING TOTAL and also report the computer time used to calculate:*) In[3]:= Timing[Total[mytestlist]] Out[3]= {0.031, 5003966} (* As you can see, for small integers, Total has a special algorithm that that adds ten times faster than just add all the numbers in order*) (* Therefore your question is equivalent to ask if there is an improved algorithm to multiply numbers, and if that algorithm is implemented in a special command in Mathematica, equivalent to Total*) (* I do not know the answer, while someone else answers this, you can multiply the following way:*) In[4]:= Times @@ mytestlist (* large result deleted *) (* The following link might be interesting for you:*) (* http://homepage.cem.itesm.mx/lgomez/matecmatica/fp/fp.html *) (* http://homepage.cem.itesm.mx/lgomez/matecmatica/funcionalprog.nb *) (* Hope that helps *) (* Jose *) (* Mexico *) -----Mensaje original----- De: Steven [mailto:steven_504 at telenet.be] Enviado el: Viernes, 11 de Abril de 2008 12:43 a.m. Para: mathgroup at smc.vnet.net Asunto: [mg87457] Product Silly beginner's question: is there a function to multiply all elements of a list, like Total does for addition? 'fraid I can't find it. TIA

**Follow-Ups**:**Re: RE: Product***From:*Andrzej Kozlowski <akoz@mimuw.edu.pl>

**References**:**Product***From:*"Steven" <steven_504@telenet.be>