A <- seq(2, 100, by = 2)
A
##  [1]   2   4   6   8  10  12  14  16  18  20  22  24  26  28  30  32  34  36  38
## [20]  40  42  44  46  48  50  52  54  56  58  60  62  64  66  68  70  72  74  76
## [39]  78  80  82  84  86  88  90  92  94  96  98 100
B <- seq(1, 100)
C <- B*(-1)^(B+1)
C
##   [1]    1   -2    3   -4    5   -6    7   -8    9  -10   11  -12   13  -14   15
##  [16]  -16   17  -18   19  -20   21  -22   23  -24   25  -26   27  -28   29  -30
##  [31]   31  -32   33  -34   35  -36   37  -38   39  -40   41  -42   43  -44   45
##  [46]  -46   47  -48   49  -50   51  -52   53  -54   55  -56   57  -58   59  -60
##  [61]   61  -62   63  -64   65  -66   67  -68   69  -70   71  -72   73  -74   75
##  [76]  -76   77  -78   79  -80   81  -82   83  -84   85  -86   87  -88   89  -90
##  [91]   91  -92   93  -94   95  -96   97  -98   99 -100
D <- matrix(1:6, nrow=2, ncol=3, byrow = TRUE)
D
##      [,1] [,2] [,3]
## [1,]    1    2    3
## [2,]    4    5    6
t <- proc.time()
s <- 1000000
cnt <- 0
for (i in 1:s){
  x <- runif(1)
  y <- runif(1)
  if (x^2 + y^2 <= 1) {
    cnt = cnt + 1
  }
}
cnt * 4 / s
## [1] 3.142004
proc.time() - t
##   ユーザ システム     経過 
##     1.80     0.28     2.22