R语言注释，最好能转为matlab语言

calculateEqualError <- function( userScores, impostorScores ) {

predictions <- c( userScores, impostorScores );
labels <- c( rep( 0, length( userScores ) ),
rep( 1, length( impostorScores ) ) );

pred <- prediction( predictions, labels );

missrates <- pred@fn[[1]] / pred@n.pos[[1]];
farates <- pred@fp[[1]] / pred@n.neg[[1]];

# Find the point on the ROC with miss slightly >= fa, and the point
# next to it with miss slightly < fa.

dists <- missrates - farates;
idx1 <- which( dists == min( dists[ dists >= 0 ] ) );
idx2 <- which( dists == max( dists[ dists < 0 ] ) );
stopifnot( length( idx1 ) == 1 );
stopifnot( length( idx2 ) == 1 );
stopifnot( abs( idx1 - idx2 ) == 1 );

y<-matrix(runif(1000*30),nrow=1000)
xm<-(rowMeans(y)-0.5)*sqrt(420)
x<-seq(-3,3,by=0.5)
F<-sum(sapply(x,function(y) xm<y))/1000
#F<-sum(c(xm< -3,xm< -2.5,xm< -2,xm< -1.5, xm< -1,xm< -0.5,xm<0,xm<0.5,xm<1,xm<1.5,xm<2,xm<2.5,xm<3))/1000
b<-pnorm(x) #b<-pnorm(seq(-3,3,by=0.5))
abs(b-F)

虽然我很聪明，但这么说真的难到我了