Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
1992
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 1992

[Date Index] [Thread Index] [Author Index]

Search the Archive

Determinant function in Mathematica

  • To: mathgroup <mathgroup at yoda.physics.unc.edu>
  • Subject: Determinant function in Mathematica
  • From: HAY at leicester.ac.uk
  • Date: Sat, 18 APR 92 11:35:30 GMT

Here's a speed up of my earlier code;  obtained by exploiting Transpose
better. The moral seems to be to work globally on large list constructions-
Think big I guess.

NewDet2[M_] := 
	Plus@@Times@@(
		Append[Transpose[Transpose[M[[#]]&/@#,{1,2,2}]],Signature/@#]&@
		Permutations[Range[Length[M]]]
	)
	
	
The timings on my MacIIfx are
	
a[n_] := Table[ StringJoin["a",ToString[i],ToString[j]], {i,1,n},{j,1,n}]

	
Do[ Print[ First[ Timing[ NewDet2[ a[t]]]]], {t,1,7}]
0.0666667 Second
0.0833333 Second
0.133333 Second
0.283333 Second
0.933333 Second
5.13333 Second
38.1833 Second
	
The timings for the previous form (NewDet) were

Do[ Print[ First[ Timing[ NewDet[ a[t]]]]], {t,1,7}]

0.25 Second
0.0833333 Second
0.15 Second
0.3 Second
1.06667 Second
5.91667 Second
43.9333 Second



From
Allan Hayes
Department of Mathematics
The University
Leicester LE1 7RH
U.K.
hay at leicester.ac.uk





  • Prev by Date: Calculus.m
  • Next by Date: Determinant Function (Final Version?)
  • Previous by thread: Re: Determinant function in Mathematica
  • Next by thread: beauty contest. the winner is...