ChebyshevTools: v=getdiag(A,n); - File Exchange

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Highlights from
ChebyshevTools

A=expD(M,ord,mod);
A_res=restrictA(A,m) this function extracts the submatrix A(1+m:end,1:end-m)
B=inv_deriv1(M); This function returns one matrix, for solving
B=inv_derivP(M,P) this function returns the Pth quasi inverse for Chebycheb differentiation
B=pseudo_eye(M,P) this function returns the pseudo-identity matrix I^(P), where there are
D=deriv(M); returns the first order chebyshev spectral differentiation matrix
D=deriv2(M);
P=cheb2poly(U) this function converts the spectral representation of a function in Chebyshev polynomials
S=stencil_mat(M,typ) this function returns the stencil matrix associated with the related
Y=cheb2phys2(X);
Y=cheb2phys3(X); 3d transform chebyshev to physical space
Y=phys2cheb2(X);
Y=phys2cheb3(X); 3d transform physical space to chebyshev
[BIG_OP,BIG_rhs]=bc_2d_new(P,... Generate the tau line boundary conditions and the appropriate rhs vector
[BIG_OP,BIG_rhs]=bc_2d_new_to... Generate the tau line boundary conditions and the appropriate rhs vector
[OP,rhs]=bc_1d(M,bc_type,bc_v...
f=galerkin2cheb(g,typ) this function transforms from the galerkin basis to the chebyshev basis
f=galerkin2cheb2(g,typ) this function transforms from the galerkin basis to the chebyshev basis in
f=galerkin2cheb3(g,typ) this function transforms from the galerkin basis to the chebyshev basis in
g=cheb2galerkin(f,typ) this function transforms from the chebyshev basis to the galerkin basis
g=cheb2galerkin2(f,typ) this function transforms from the galerkin basis to the chebyshev basis in
g=cheb2galerkin3(f,typ) this function transforms from the galerkin basis to the chebyshev basis in
test_problem(M,N,tc) This function is run from the command line taking argumetns
v=getdiag(A,n); extract the nth diag from matrix A
x=cheb_grid(N); this function returns a chebyshev grid on the interval [-1,1]
y=cheb2phys(F); Written by Mike Watson, November 29
y=definite_integral_cart(F,X1... Calculate the definite integral of a function defined by spectral
y=myC(p)
y=phys2cheb(f); Written by Mike Watson, November 29
deriv3.m
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from ChebyshevTools by Michael Watson
Tool box for solving ODE/PDEs using spectral Chebyshev differentiation matrices.

v=getdiag(A,n);

function v=getdiag(A,n);

%extract the nth diag from matrix A
% n = 0 main diag

absn=abs(n);

M=max(size(A));

v=zeros(M-absn,1);


if (n>=0)
   for j=1:M-absn
      v(j,1)=A(j,j+n);     
   end
else
    for j=absn+1:M
      v(j-absn,1)=A(j,j+n);     
   end
end

Highlights from ChebyshevTools

Highlights from
ChebyshevTools