@Preben Alsholm 

i don't have any problem ! Just i want to know which numeric methods is used in my solution

@Carl Love 

diff(T(x, y), x)2*(diff(T(x, y), y, y))/(5*y^2+6*y-0.6e-3)-2.392344498*10^(-10)*(8*y+1.604738400*10^7)^2/(5*y^2+6*y-0.6e-3) = 0

please help freinds........

no answer...... ?

>

pdsolve/fdscheme/ThetaOdd: Deriving 3-point (space) theta scheme for input PDE

pdsolve/default/construct_method:

@acer 

thank u i got it

@acer 

and for this examlpe :

pde := diff(T(x, y), x)-2*(diff(T(x, y), y, y))/(-2*y^2+3*y-1)-20*(5+6)^2/(-2*y^2+3*y-1) = 0

sol := pdsolve(pde, {T(0, y) = 0, (D[2](T))(x, 0) = 100, (D[2](T))(x, 0.25) = 100}, numeric)

how can i get infolevel ??

@dharr 

thakn u , i konw that :

The pdsolve/numeric routine uses finite difference methods to obtain these numerical solutions and The values of both options ( Time & Range ) are determined automatically if the boundary conditions are specified for both end points of the domain.

and i wana know how can i see the value that determined automatically .

thanks.

@Preben Alsholm 

thanks alot Preben Alsholm 6520

i have one more quastion :D

i solved my equation , T(x,y) , as fellow :

pde := diff(T(x, y), x)-1.775*10^(-5)*(diff(T(x, y), y, y))/(-1.218493440*10^11*y^2+4.244913600*10^6*y+0.6e-3) = 0

sol := pdsolve(pde, {T(0, y) = 0, (D[2](T))(x, 0) = 1000, (D[2](T))(x, 0.25e-4) = 2000}, numeric)

sol:-plot3d(x = 0 .. 0.175e-1)

and now how can i use my solve to obtain enother parameters as fellow  : 

h=100/T(x,y)

@Preben Alsholm 

so what can i do ? waht's your idea about define a function ? , for example :

diff(T(x,y),y)=M(x,y) and boundary condition be D[1](M)(x,0)=1000 

@Preben Alsholm 

i mean D[1](T)(x,0)=1000 and D[1](T)(x,0.000025)=2000 NO D[2]

@Preben Alsholm 

i trying to solve a model that folw is between the tow plate which are in different heat flux , so i have this BC :

BC1 = diff(T(x, 0), y)=1000

BC2 = diff(T(x, 0.000025), y)=2000

BC3 = diff(T(x, 0.000025), x)=0

IC = T(0,y)=0

@Preben Alsholm 

 my full problem is :

sol1 := [diff(T(x, y), x)-1.775*10^(-5)*(diff(T(x, y), y, y))/(-1.218493440*10^11*y^2+4.244913600*10^6*y+0.33e-1) = 0, T(0, y) = 0, (D[1](T))(0, y) = 1000, (D[1](T))(x, 0) = 2000]

i have this error :

Error, (in pdsolve/numeric/process_IBCs) initial/boundary conditions can only contain derivatives which are normal to the boundary, got (D[1](T))(x, 0)

@Markiyan Hirnyk i used in matlab but i could solve again !

@Markiyan Hirnyk 

i did as follow :

@Markiyan Hirnyk i didn't know what u mean !

my full integral is : int(1/(1-exp(a*x)*erfc(a*x^1/2),x=0..1000) and a=114808.7208