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These are replies submitted by adel-00

@Carl Love 

thanks for ur valuable comments 

I did like this

xyz := solve([a11*x+a12*y+a13*z = b1, a21*x+a22*y+a23*z = b2, a31*x+a32*y+a33*z = b3], [x, y, z]);

P1 := plot3d(eval(z, xyz[]), viewpoint = ["circleleft", frames = 20], title = "z"); plottools:-getdata(P1); A := %[-1]; mx := max(A); tr := plottools:-transform(proc (x, y, z) options operator, arrow; [x, y, z/mx] end proc); tr(P1);
becouse there is very big numbers..

if to make contours in the above plot at z=0.5

contourplot(eval(z, xyz[]), theta = .1 .. 3, phi = 0 .. 2*Pi, contours = [.5])

is it right?


@Carl Love 

Thanks it is the brackets[

can you please the plot3d what is the problem here.



no complex number at all

@Ali Guzel  

it is run for 20 min then i stop , i think that is not work



do u mean explicit(solve(K1=0,R));

still no roots

@Rouben Rostamian  

The resean is to find the coefficients of the Expression 


CoefficientList(r, (D[1](Q))(x*H2(t), H3(t)))


I change the ics to be function of x.. that is error


Thank you for your help..

I made changes in the Ics

still i had an error

assume(x, real); assume(t, real):
  sys:= { -diff(v(x,t),t)+0.5*p*diff(u(x,t),x,x)+q*u(x,t)*(u(x,t)^2+v(x,t)^2)=0,
  bc:= u(0,t) = 2,
       v(0,t) = 0,
       u(1,t) = 0,  # made this up
       v(1,t) = 0;  # made this up
  ic := u(x,0) = 4.999999999*10^9*cosh(1.414213562*x)/(3.535533906*10^9*cosh(1.414213562*x)-5.000000000*10^9),
        v(x,0) = 0;
  pdsol := pdsolve(eval(sys, [p=1, q=0.5]), {ic, bc}, numeric);
  p1:= pdsol:-plot3d( u(x,t), x=0..1, t=0..5, color=red, style=surface, transparency=0.5):
  p2:= pdsol:-plot3d( v(x,t), x=0..1, t=0..5, color=blue, style=surface, transparency=0.5):

{diff(u(x, t), t)+.5*p*(diff(diff(v(x, t), x), x))+q*v(x, t)*(u(x, t)^2+v(x, t)^2) = 0, -(diff(v(x, t), t))+.5*p*(diff(diff(u(x, t), x), x))+q*u(x, t)*(u(x, t)^2+v(x, t)^2) = 0}


u(0, t) = 2, v(0, t) = 0, u(1, t) = 0, v(1, t) = 0


u(x, 0) = 4999999999.*cosh(1.414213562*x)/(3535533906.*cosh(1.414213562*x)-5000000000.), v(x, 0) = 0




Error, (in pdsolve/numeric/plot3d) unable to compute solution for t>HFloat(0.0):
Newton iteration is not converging


Error, (in pdsolve/numeric/plot3d) unable to compute solution for t>HFloat(0.0):
Newton iteration is not converging


Error, (in plots:-display) expecting plot structures but received: [p1, p2]







I dont know what is the error


Many thanks


Many thanks

@Carl Love 

here the approximation is real

Yp  := k -> (y[k+1]-y[k-1])/2/((1+alpha)*GAMMA(1+alpha)*h^(alpha)):Ypp := k -> (y[k+1]-2*y[k]+y[k-1])/((2-alpha)*GAMMA(2-alpha)*(h^(2-alpha))^2):


@Carl Love 

yes you are right but what can i do maybe there is somthing to do with sequence or the loop

or k from 1 to N-1 do
eq[k] := eval( ode1,
                    {x=X(k), y(x)=y[k],
                     diff(y(x),x$2)=Ypp(k)} ):
    end do:


thank you very much

n(t) is real

  • Do you want to plot n(t) versus t for a countable set of delta values in 3D-like representation (a solution is given below)? Yes this is the case


Thanks for all the comments

 how we can plot 3d of n(t) agianst t and delta

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