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 38.532 38.743 39.27145 38.8630 39.148 49.472   100
#>     r 25.287 25.748 26.07290 25.8935 26.109 32.841   100