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] 9876.546

# Compare speed
microbenchmark::microbenchmark(
  cpp = {sumsquared(x)},
  r = {sum(x^2)}
)
#> Unit: microseconds
#>  expr    min      lq     mean median      uq    max neval
#>   cpp 26.545 26.6025 26.97274 26.661 26.7625 36.876   100
#>     r 15.985 17.1370 18.10019 17.599 18.1830 30.617   100