From: Jaime Villate <villate@fe...>  20140604 12:30:08

On 04062014 09:36, message wrote: > ve:(solve(va=vd,vx)); > [vx = 15] OK, the symbol ve is now associated to a list, with only one element and that element is the equation "vx=15" Notice that vx is still a symbol that has no value associated to it. Values are associated to symbols using the operator ":" and not with "=". > ve=(solve(va=vd,vx)); > [vx = 15] = [vx = 15] no, that makes no sense. > > What is the correct instruction to return a number result please (i.e. > %o... 15)? Since 15 is the right hand side of the equation "vx=15", which is the first element in the value associated to the symbol ve, you must use rhs(ve[1]). If you want to use it in the plot command you showed yesterday, type: plot2d (vf, [vx, 0, rhs ( ve[1]) ] ); you could also associate the result 15 to a symbol: symbol: rhs(ve[1]); and then use it when you need it: plot2d (vf, [vx, 0, symbol] ); Jaime 