loncom/homework/functionplotresponse.pm - diff

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version 1.33, 2010/11/11 03:52:35	version 1.34, 2010/11/11 15:57:49
Line 639 sub populate_arrays {	Line 639 sub populate_arrays {
my $dxdt=&ddt_cubic_hermite($t,@xparms);	my $dxdt=&ddt_cubic_hermite($t,@xparms);
if ($dxdt) {	if ($dxdt) {
$Apache::functionplotresponse::dfuncdx[$xi]=&ddt_cubic_hermite($t,@yparms)/$dxdt;	$Apache::functionplotresponse::dfuncdx[$xi]=&ddt_cubic_hermite($t,@yparms)/$dxdt;
}	# Second derivative
# Faa di Bruno
# d^2y/dx^2=(d^2y/dt^2)/(dx/dt)^2+(dy/dt)/(d^2x/dt^2)
my $d2xdt2=&d2dt2_cubic_hermite($t,@xparms);
if (($dxdt) && ($d2xdt2)) {
$Apache::functionplotresponse::d2funcdx2[$xi]=	$Apache::functionplotresponse::d2funcdx2[$xi]=
&d2dt2_cubic_hermite($t,@yparms)/($dxdt*$dxdt)	($dxdt&d2dt2_cubic_hermite($t,@yparms)-&ddt_cubic_hermite($t,@yparms)&d2dt2_cubic_hermite($t,@xparms))/
+&ddt_cubic_hermite($t,@yparms)/$d2xdt2;	($dxdt$dxdt$dxdt);
}	}
}	}
}	}