set.seed(1)
options(digits=4)
mA <- matrix(runif(16), 4, 4); mA
[,1] [,2] [,3] [,4]
[1,] 0.266 0.202 0.6291 0.687
[2,] 0.372 0.898 0.0618 0.384
[3,] 0.573 0.945 0.2060 0.770
[4,] 0.908 0.661 0.1766 0.498
mB <- matrix(runif(16), 4, 4); mB
[,1] [,2] [,3] [,4]
[1,] 0.718 0.935 0.2672 0.870
[2,] 0.992 0.212 0.3861 0.340
[3,] 0.380 0.652 0.0134 0.482
[4,] 0.777 0.126 0.3824 0.600
mC <- mA
mC[mB>0.05] <- NA; mC
[,1] [,2] [,3] [,4]
[1,] NA NA NA NA
[2,] NA NA NA NA
[3,] NA NA 0.206 NA
[4,] NA NA NA NA