To complement Christian’s answer, let me recall what \uppercase
does.
When you do \uppercase{<text>}
, the characters in <text>
(as opposed to commands) are converted to their uppercase equivalent as established by a vector loaded into memory.
For example, a
will turn into A
, because the vector contains, at the slot 0x61
the value 0x41
; on the other hand commas and so on will not change, because in the corresponding slots the vector has 0 (which is the marker telling TeX not to change the character).
Now, for LaTeX, a tau is not a single character, but two (due to UTF-8), precisely the characters in slots 0xCF
and 0x84
(hexadecimal).
Here is the correspondence table when LaTeX starts up:
80->80 81->81 82->82 83->83 84->84 85->85 86->86 87->87
88->88 89->89 8A->8A 8B->8B 8C->8C 8D->8D 8E->8E 8F->8F
90->90 91->91 92->92 93->93 94->94 95->95 96->96 97->97
98->98 99->99 9A->9A 9B->9B 9C->9C 9D->9D 9E->D0 9F->0
A0->80 A1->81 A2->82 A3->83 A4->84 A5->85 A6->86 A7->87
A8->88 A9->89 AA->8A AB->8B AC->8C AD->8D AE->8E AF->8F
B0->90 B1->91 B2->92 B3->93 B4->94 B5->95 B6->96 B7->97
B8->98 B9->99 BA->9A BB->9B BC->9C BD->0 BE->0 BF->0
C0->C0 C1->C1 C2->C2 C3->C3 C4->C4 C5->C5 C6->C6 C7->C7
C8->C8 C9->C9 CA->CA CB->CB CC->CC CD->CD CE->CE CF->CF
D0->D0 D1->D1 D2->D2 D3->D3 D4->D4 D5->D5 D6->D6 D7->D7
D8->D8 D9->D9 DA->DA DB->DB DC->DC DD->DD DE->DE DF->DF
E0->C0 E1->C1 E2->C2 E3->C3 E4->C4 E5->C5 E6->C6 E7->C7
E8->C8 E9->C9 EA->CA EB->CB EC->CC ED->CD EE->CE EF->CF
F0->D0 F1->D1 F2->D2 F3->D3 F4->D4 F5->D5 F6->D6 F7->D7
F8->D8 F9->D9 FA->DA FB->DB FC->DC FD->DD FE->DE FF->DF
(just the characters beyond 0x7F
are shown here). There are reasons behind these values, but it would take too long to explain them.
Anyway, you see that 0xCF
and 0x84
don't change, so a tau will remain unchanged. On the other hand a kappa is input as 0xCE
and 0xBA
; the first part doesn't change, the second one becomes 0x9A
and the combination 0xCE
followed by 0x9A
in UTF-8 is indeed an uppercase Greek kappa.
There's no way this can work for every UTF-8 character; moreover, control sequences would remain the same, which would be a nuisance for other languages (for instance, in German \ss
should become \SS
, for proper output).
Thus LaTeX has introduced \MakeUppercase
that “does the right thing”, using \uppercase
in some cases, a different conversion table in others.
Similarly, \lowercase
should not be used in LaTeX: the correct command is \MakeLowercase
.
LGR
is not necessary. – egreg Jun 3 '17 at 17:30\usepackage[T1]{fontenc}
is needed, or is that unnecessary too? – svart Jun 3 '17 at 17:34