26
Le logiciel R
Choisis un nombre parmi 1, 2, 3: 1
[1] "Bien joué!"
> ls()
[1] "adeviner" "chaine"
"L"
"M"
"value"
[6] "x"
> rm(chaine)
Les commandes ci-dessous permettent d’effectuer certaines op´ erations sur des
matrices.
> A <- matrix(runif(9),nrow=3)
> 1/A
[,1]
[,2]
[,3]
[1,] 3.642582 2.327359 8.809875
[2,] 3.672352 1.534553 1.678063
[3,] 1.623827 1.761377 2.792906
> A * (1/A)
[,1] [,2] [,3]
[1,]
1
1
1
[2,]
1
1
1
[3,]
1
1
1
> B <- matrix(1:12,nrow=3)
> A * B # Renvoie une erreur.
Error in A * B : tableaux de tailles inadéquates
> A % * % B
[,1]
[,2]
[,3]
[,4]
[1,] 1.474401 3.927534 6.380667 8.83380
[2,] 3.363392 7.923050 12.482709 17.04237
[3,] 2.825455 7.450306 12.075157 16.70001
> (invA <- solve(A)) # Notez l’ajout de parenthèses et son effet!
[,1]
[,2]
[,3]
[1,] -1.780899 -1.5162594 3.088187
[2,] 4.570620 0.4815619 -2.250472
[3,] -4.184287 1.8443127 1.049802
> A % * % invA
[,1]
[,2]
[,3]
[1,]
1 5.551115e-17 0.000000e+00
[2,]
0 1.000000e+00 -1.110223e-16
[3,]
0 0.000000e+00 1.000000e+00
> det(A)
[1] 0.05896125
> eigen(A)
$values
[1] 1.3287063+0.0000000i -0.0222351+0.2094768i
[3] -0.0222351-0.2094768i
$vectors
[,1]
[,2]
[,3]
[1,] 0.3506486+0i 0.0314831+0.5389506i 0.0314831-0.5389506i
[2,] 0.6942529+0i -0.4475357-0.3568936i -0.4475357+0.3568936i
[3,] 0.6285368+0i 0.6171547+0.0000000i 0.6171547+0.0000000i