pretty printer display for 'at(..., x = foo) cuts off foo if it is taller than vertical bar

[rtoy]

Imported from SourceForge on 2024-07-09 20:03:04
Created by robert_dodier on 2023-12-28 21:38:16
Original: https://sourceforge.net/p/maxima/bugs/4233

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The 2-d pretty printer omits part of the display of foo if foo is taller than the vertical bar in 'at(..., x = foo). Here are some examples:

(%i3) 'at(u, u=((1 - y)/(1 + y) + 1)/(1 - (1 - x)/(1 + x)));
                          !    ----- + 1
(%o3)                    u!    y + 1
                          !u = ---------
                                   1 - x
                               1 - -----
                                   x + 1
(%i4) 'at(u, u=matrix ([n, 'sum(x[k],k,1,n)], ['sum(x[k],k,1,n), 'sum(x[k]^2,k,1,n)]));
                   !    [           ====     ]
(%o4)             u!    [           k = 1    ]
                   !u = [                    ]
                        [  n         n       ]
                        [ ====      ====     ]
                        [ \         \      2 ]
                        [  >    x    >    x  ]
                        [ /      k  /      k ]
                        [ ====      ====     ]
                        [ k = 1     k = 1    ]
(%i5) 'at(u, u=a^b^c^d^e);
                            !      c
(%o5)                      u!     b
                            !u = a

I guess what needs to happen is to shift the whole expression down so that there is enough room to display all of the right hand side of the equation.

Observed with Maxima built from commit 3a26747, which, for the record, is before the recent Unicode display stuff; the Unicode display exhibits the same bug.