Question: How to plot Contour

with(plots); R1 := .1; R0 := .1; m := .1; a := .1; Ha := .1; Nt := .1; Nb := .1; Pr := 6.2; Le := .6; Bi := 1; Ec := .1; k := 1; r := .1; A := 1; fcns := {C(y), T(y), U(y), W(y)}; sys := diff(U(y), `$`(y, 2))+(R1*(diff(U(y), y))-2*R0*W(y))*exp(a*T(y))-a*(diff(U(y), y))*(diff(T(y), y))-Ha*(U(y)+m*W(y))*exp(a*T(y))/(m^2+1)-U(y)/k+A*exp(a*T(y)) = 0, diff(W(y), `$`(y, 2))+(R1*(diff(W(y), y))+2*R0*U(y))*exp(a*T(y))-a*(diff(W(y), y))*(diff(T(y), y))-Ha*(W(y)-m*U(y))*exp(a*T(y))/(m^2+1)-W(y)/k = 0, diff(T(y), `$`(y, 2))+R1*Pr*(diff(T(y), y))+Pr*Ec*exp(-a*T(y))*((diff(U(y), y))*(diff(U(y), y))+(diff(W(y), y))*(diff(W(y), y)))+Nt*(diff(T(y), y))*(diff(T(y), y))+Pr*Ec*(U(y)*U(y)+W(y)*W(y))*exp(-a*T(y))/k = 0, diff(C(y), `$`(y, 2))+Pr*Le*R1*(diff(C(y), y))+Nt*(diff(C(y), `$`(y, 2)))/Nb-r*C(y) = 0; bc := U(0) = 0, W(0) = 0, C(0) = 0, (D(T))(0) = Bi*(T(0)-1), U(1) = 0, W(1) = 0, C(1) = 1, T(1) = 0; L := [.5, 1.0, 1.5, 2.0]; AP := NULL; for k to 4 do R := dsolve(eval({bc, sys}, Ha = L[k]), fcns, type = numeric, method = bvp[midrich], AP); AP := approxsoln = R; p1u[k] := odeplot(R, [y, U(y)], 0 .. 1, numpoints = 100, labels = ["y", "U"], linestyle = dash, color = black) end do; display({p1u[1], p1u[2], p1u[3], p1u[4]})