I'm not sure I understand what you are asking, but I will take a shot. If f(x) is a function whose range goes from $f_min to $f_max over the domain of interest, and the graph is of size $graph_size, then plot

my $span = $f_max - $f_min;
$y = (-f($x)-$f_min)*$graph_size/$span;

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In the case of your sine, you would have $f_min = -1; $f_max = 1; $graph_size = 400. This simplifies the the expression in my previous response.

In reply to Re^7: Make sin wave with GD by sn1987a
in thread Make sin wave with GD by Anonymous Monk

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