# nsolve is numeric solve equation;
# x0 is initial value;


nsolve(y_):=nsolve(y,x,1);

nsolve(y_,x_=x0_):= nsolve(y,x,x0);
nsolve(left_=r_, x_) := (x=nsolve(left-r, x));
nsolve(left_=r_, x_=x0_) := nsolve(left-r, x,x0);
nsolve(left_=r_) := nsolve(left-r);