Ketinit();

Ospline("1",[A,B,C,D]);
Putoncurve("P","bzo1");
m=Derivative("bzo1","x="+P.x);
//Lineplot("1",[P,P+[1,m]]);
//Defvar("m",m);
//Plotdata("1","m*(x-P.x)+P.y","x",["Num=1"]);
fun=Assign("m*(x-P.x)+P.y",["m",m]);
Plotdata("1",fun,"x",["Num=1"]);
Windispg();

//Help("Deri");