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#!/usr/bin/env r
suppressMessages(library(Rcpp))
suppressMessages(library(inline))
foo <- '
int i, j, na, nb, nab;
double *xa, *xb, *xab;
SEXP ab;
PROTECT(a = AS_NUMERIC(a));
PROTECT(b = AS_NUMERIC(b));
na = LENGTH(a); nb = LENGTH(b); nab = na + nb - 1;
PROTECT(ab = NEW_NUMERIC(nab));
xa = NUMERIC_POINTER(a); xb = NUMERIC_POINTER(b);
xab = NUMERIC_POINTER(ab);
for(i = 0; i < nab; i++) xab[i] = 0.0;
for(i = 0; i < na; i++)
for(j = 0; j < nb; j++) xab[i + j] += xa[i] * xb[j];
UNPROTECT(3);
return(ab);
'
funx <- cfunction(signature(a="numeric",b="numeric"), foo, Rcpp=FALSE, verbose=FALSE)
funx(a=1:20, b=2:11)
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