Dear Ana,
f[x_] = x^2;
a = 0;
b = 1;
n = 2^m;
\[CapitalDelta]x = (b - a)/n;
nn = PaddedForm[n, 10];
temp1 = PaddedForm[N[ \!\(
\*UnderoverscriptBox[\(\[Sum]\), \(i = 1\), \(n\)]\(f[
a + \((i - 1)\)*\[CapitalDelta]x]\ \[CapitalDelta]x\)\)], {8,
6}];
temp2 = PaddedForm[N[\!\(
\*UnderoverscriptBox[\(\[Sum]\), \(i = 1\), \(n\)]\(f[
a + i*\[CapitalDelta]x]\ \[CapitalDelta]x\)\)], {8, 6}];
list = Table[{nn, temp1, temp2}, {m, 1, 20}];
TableForm[list, TableSpacing -> {1, 5},
TableHeadings -> {None, {"n", "Lower", "Upper"}},
TableAlignments -> Right]
appears to be doing something similar to what you do with the spaces. The "n" appears to be aligned like you want. The "upper" and "lower" are a bit more to the right, with this automatic choice. You can also use
TableAlignments -> Center
and see whether you like that better. Check also the documentation entry for "TableAlignments".
M.
