37 lines
907 B
R
37 lines
907 B
R
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library(foreach)
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# Define a function that creates an iterator that returns subvectors
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ivector <- function(x, chunks) {
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n <- length(x)
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i <- 1
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nextEl <- function() {
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if (chunks <= 0 || n <= 0) stop('StopIteration')
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m <- ceiling(n / chunks)
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r <- seq(i, length=m)
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i <<- i + m
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n <<- n - m
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chunks <<- chunks - 1
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x[r]
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}
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obj <- list(nextElem=nextEl)
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class(obj) <- c('abstractiter', 'iter')
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obj
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}
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# Define the coordinate grid and figure out how to split up the work
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x <- seq(-10, 10, by=0.1)
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cat('Running sequentially\n')
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ntasks <- 4
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# Compute the value of the sinc function at each point in the grid
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z <- foreach(y=ivector(x, ntasks), .combine=cbind) %do% {
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y <- rep(y, each=length(x))
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r <- sqrt(x ^ 2 + y ^ 2)
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matrix(10 * sin(r) / r, length(x))
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}
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# Plot the results as a perspective plot
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persp(x, x, z, ylab='y', theta=30, phi=30, expand=0.5, col="lightblue")
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