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] 10007.41

# Compare speed
microbenchmark::microbenchmark(
  cpp = {sumsquared(x)},
  r = {sum(x^2)}
)
#> Unit: microseconds
#>  expr    min      lq     mean  median     uq    max neval
#>   cpp 37.860 37.9500 38.65478 38.1015 38.251 52.528   100
#>     r 24.786 25.1215 25.76425 25.3870 25.763 34.534   100