use strict;
use warnings;
use Math::BigInt;

use Inline C => Config =>
 BUILD_NOISY => 1,
 USING => 'ParseRegExp',
 CLEAN_AFTER_BUILD => 0,
 ;

use Inline C => <<'EOC';


double do_nothing(SV * x, ...)
{
  dXSARGS; /* enable stack manipulation */
  int index;
  for(index=0; index<items; index++)
  {
    printf("%f ", SvNV(ST(index)));
    ST(index)=newSVnv(1.34);
  }
  printf("\n");
  return SvNV(ST(0));
}

EOC

my @in = (2.3, 3.4, 4.5, 6.8);
my $d = do_nothing(@in);
print $d, "\n";

my @next = (-1.7, -1.3, @in);
my $d2 = do_nothing(@next);
print $d2, "\n";

__END__
Outputs:
2.300000 3.400000 4.500000 6.800000
1.34
-1.700000 -1.300000 2.300000 3.400000 4.500000 6.800000
1.34


##</code><code>##

double do_nothing(SV * x) {
  ... do stuff
}

##</code><code>##

my $double = do_nothing(\@in);