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RANDU: the bad random number generator
N = 1000
randu = matrix(0, ncol=3, nrow=N)
##Simulate from the randu random number generator
new_z = 1
for(i in 1:N) {
new_x = (65539*new_z) %% 2^31
new_y = (65539*new_x) %% 2^31
new_z = (65539*new_y) %% 2^31
randu[i,] = c(x=new_x/2^31, y=new_y/2^31,
z=new_z/2^31)
}
##Simulate from the RNG in R
g = matrix(0, ncol=3, nrow=N)
for(i in 1:N) {
new_x = runif(1)
new_y = runif(1)
new_z = runif(1)
g[i,] = c(x_g=new_x, y_g=new_y, z_g=new_z)
}
##Plot the results
op = par(mfrow=c(1, 2), mar=c(3,3,2,1),
mgp=c(2,0.4,0), tck=-.01,
cex.axis=0.9, las=1)
plot(randu[,3], 9*randu[,1] - 6*randu[,2], ylim=c(-6, 10),
xlab="", ylab="", cex=0.5,panel.first=grid(), pch=21, bg="#5582A9",
frame=FALSE, axes=FALSE, lwd=0.5)
title("RANDU", adj=0, cex.main=1.2, font.main=2, col.main="black")
plot(g[,3], 9*g[,1] - 6*g[,2], ylim=c(-6, 10),
xlab="", ylab="", cex=0.5,panel.first=grid(), pch=21, bg="#5582A9",
frame=FALSE, axes=FALSE, lwd=0.5)
title("Standard rng", adj=0, cex.main=1.2, font.main=2, col.main="black")
par(op)
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