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I have a matrix in C++

Matrix<double> A = {
    {31, -13, 0, 0, 0, -10, 0, 0, 0},
    {-13, 35, -9, 0, -11, 0, 0, 0, 0},
    {0, -9, 31, -10, 0, 0, 0, 0, 0},
    {0, 0, -10, 79, -30, 0, 0, 0, -9},
    {0, 0, 0, -30, 57, -7, 0, -5, 0},
    {0, 0, 0, 0, -7, 47, -30, 0, 0},
    {0, 0, 0, 0, 0, -30, 41, 0, 0},
    {0, 0, 0, 0, -5, 0, 0, 27, -2},
    {0, 0, 0, -9, 0, 0, 0, -2, 29}
};

Tried M-- M-x align but that gives

Matrix<double> A = {
    {31,  -13, 0,   0,   0,   -10, 0,   0,  0},
    {-13, 35,  -9,  0,   -11, 0,   0,   0,  0},
    {0,   -9,  31,  -10, 0,   0,   0,   0,  0},
    {0,   0,   -10, 79,  -30, 0,   0,   0,  -9},
    {0,   0,   0,   -30, 57,  -7,  0,   -5, 0},
    {0,   0,   0,   0,   -7,  47,  -30, 0,  0},
    {0,   0,   0,   0,   0,   -30, 41,  0,  0},
    {0,   0,   0,   0,   -5,  0,   0,   27, -2},
    {0,   0,   0,   -9,  0,   0,   0,   -2, 29}
};

which is not particularly visually-appealing! How can I align elements to the right? (,s on one column)

  • What's the value of align-rules-alist (C-h v RET align-rules-alist RET)? Are you running M-x align with a prefix argument (e.g. using C-u M-x align-rules alist in vanilla emacs, or 4 SPC SPC align-rules-alist in spacemacs)? – Croad Langshan Dec 2 '18 at 16:16
  • I think what's happening is that emacs is trying to line up the numbers, not the end of the lines, and regards the - in numbers as part of the thing that should be aligned. The details of alignment behaviour are I think configured by align-rules-alist. I guess it's working the way you see in part because of the value of that variable (in particular, c-comma-delimiter). – Croad Langshan Dec 2 '18 at 16:19
  • @CroadLangshan Vanilla emacs with the default rules list. I still have no idea how alignment in Emacs works. But thanks to your tip I now know that emacs is trying to capture whitespaces... If align doesn't work, how can I solve it by align-regexp? – Mike Manilone Dec 3 '18 at 9:25

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