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view +sbp/diagInd.m @ 255:df3cc9c5dffc operator_remake

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Added ordinary 12th order accurate, with D1*D1 as 2nd derivative.
author Martin Almquist <martin.almquist@it.uu.se>
date Wed, 07 Sep 2016 15:54:41 +0200
parents 32b39dc44474
children
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function A = diagInd(d,n,m)
    A = zeros(n,length(d));
    for i = 1:length(d)
        i0 = 1;
        j0 = d(i)+1;

        I = i0 + (0:(n-1))';
        J = j0 + (0:(n-1))';

        A(:,i) = matInd2VecInd(I,J,n);

    end
end

function I = matInd2VecInd(i,j,n)
    I = i + (j-1)*n;
end