f:=(t,y)->exp(t)*sin(y);Euler:=proc(ystart,tstart,tstop,deltat)
local t,y0,y1;
global results;
t:=tstart;
y0:=ystart;
results:=[[tstart,ystart]];
while t < tstop do
y1:=evalf(y0+f(t,y0)*deltat);
t:=evalf(t+deltat);
results:=[op(results),op([[t,y1]])];
y0:=y1;
end do;
end proc;