Change computation of "y": y = (m*p)./(p + (m - p)*exp(-k*m*t)); The dot before "/" is very important here. Kind Regards, Longin Horodko -- View this message in context: http://mailinglists.scilab.org/Scilab-users-help-a-newbie-out-tp4028211p4028214.html Sent from the Scilab users - Mailing Lists Archives mailing list archive at Nabble.com.