Perl - 161 (working program)
($s,$n,$m)=@ARGV;$i=$s;@a=qw(/ \\);--$a;do{$r.=sprintf("%${i}s".' 'x(($s-$i)*2)."%-${i}s",@a)x$n."\n";$i=1,$a=-$a,@a=@a[-1,0]unless$i+=$a}while$i<=$s;print$r x$m
Perl - 119 (second variant)
It's more cool idea... I'm using ability of interpolation of arrays to strings.
($s,$n,$m)=@ARGV;map{@a=@b=('')x$s;$a[-$_]='/';$b[$_-1]='\\';$z.="@a@b"x$n."\n";$x.="@b@a"x$n."\n"}1..$s;print"$z$x"x$m
Full second variant:
my ($s,$n,$m) = @ARGV; # take command line parameters
my ($z,$x); # variables for upper and lower parts of diamond
for (1..$s) { # lines of half diamond
my (@a,@b); # temporary arrays
@a=@b=('')x$s; # fill arrays with empty strings
$a[-$_]='/'; # left part of diamond
$b[$_-1]='\\'; # rigth part of diamond
$z .= "@a@b" x $n . "\n"; # adding n upper parts of diamonds
$x .= "@b@a" x $n . "\n"; # adding n lower parts of diamonds
}
print "$z$x" x $m; # "$z$x" - horizontal line of diamonds
