Merwan Behar Hello.

[D]=Diff_Quad(N);

Differential Quadrature Matrix for 1st derivative based on Lobatto grid.It calculates for N grid points.Higher derivatives can be easily calculated by using D matrix.

Or this might work: (as an example)

function [D]=Diff_Quad(N)

%

% Differential quadrature matrix for N

% points based on Lobatto grid points.

% D matrix converts the diff. equation into eigenvalue problem.

% y'=A*y --> Dy=Ay

%

%

% For any questions and critiques

% [email protected]

% Altug Bicak @ 2005

for ii=1:N

X(ii)=0.5*(1-cos((ii-1)*pi/(N-1)));

end

SagTaraf=1;

Taraf=0;

for ii=1:N

for jj=1:N

if ii~=jj

a1=(1/(X(jj)-X(ii)));

for k=1:N

if k~=ii & k~=jj

SagTaraf=SagTaraf*(X(ii)-X(k))/(X(jj)-X(k));

end

end

a(ii,jj)=a1*SagTaraf;

SagTaraf=1;

end

if ii==jj

for k=1:N

if k~=ii

Taraf=Taraf+(1/(X(ii)-X(k)));

end

end

a(ii,jj)=Taraf;

Taraf=0;

end

end

end

D=a;

tic

Merwan Behar Hello.

[D]=Diff_Quad(N);

Differential Quadrature Matrix for 1st derivative based on Lobatto grid.It calculates for N grid points.Higher derivatives can be easily calculated by using D matrix.

Or this might work: (as an example)

function [D]=Diff_Quad(N)

%

% Differential quadrature matrix for N

% points based on Lobatto grid points.

% D matrix converts the diff. equation into eigenvalue problem.

% y'=A*y --> Dy=Ay

%

%

% For any questions and critiques

% [email protected]

% Altug Bicak @ 2005

for ii=1:N

X(ii)=0.5*(1-cos((ii-1)*pi/(N-1)));

end

SagTaraf=1;

Taraf=0;

for ii=1:N

for jj=1:N

if ii~=jj

a1=(1/(X(jj)-X(ii)));

for k=1:N

if k~=ii & k~=jj

SagTaraf=SagTaraf*(X(ii)-X(k))/(X(jj)-X(k));

end

end

a(ii,jj)=a1*SagTaraf;

SagTaraf=1;

end

if ii==jj

for k=1:N

if k~=ii

Taraf=Taraf+(1/(X(ii)-X(k)));

end

end

a(ii,jj)=Taraf;

Taraf=0;

end

end

end

D=a;

tic

thank you so much Shahida Anusha Siddiqui