The d A (calc-giac-language) command selects the
conventions of Giac, another free computer algebra system. The function
names in Giac are similar to Maxima. Complex numbers are written
‘3 + 4 i’. The standard special constants in Giac are the same as
in Calc, except that infinity represents both Calc’s inf
and uinf.
Underscores are allowed in function and variable names in Giac mode. Brackets are used for subscripts. In Giac, indexing of lists begins at 0, instead of 1 as in Calc. So if ‘A’ represents the list ‘[a,2,c,4]’, then ‘A[2]’ would equal ‘c’. In general, ‘A[n]’ in Giac mode corresponds to ‘A_(n+1)’ in Normal mode.
The Giac interval notation ‘2 .. 3’ has no surrounding brackets; Calc reads ‘2 .. 3’ as the closed interval ‘[2 .. 3]’ and writes any kind of interval as ‘2 .. 3’. This means you cannot see the difference between an open and a closed interval while in Giac mode.