Fast Calculation of Sum-squared for Large Matrices/Vectors

Calculate sum(x^2), but faster when the number of elements exceeds 1000.

Arguments

x

double, integer, or logical vector/matrix

Value

A numerical scalar

Examples

x <- rnorm(10000)
sumsquared(x)
#> [1] 9893.091

# Compare speed
microbenchmark::microbenchmark(
  cpp = {sumsquared(x)},
  r = {sum(x^2)}
)
#> Unit: microseconds
#>  expr    min      lq     mean  median      uq    max neval
#>   cpp 37.830 37.9210 38.81193 38.1060 38.3965 52.418   100
#>     r 24.536 24.8715 25.66799 25.2475 25.6730 41.488   100