From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Fri,  2 Jun 1995 14:44:13 -0400
From: rob@plan9.att.com rob@plan9.att.com
Subject: No subject
Topicbox-Message-UUID: 0eb8acb6-eac8-11e9-9e20-41e7f4b1d025
Message-ID: <19950602184413.xptfEGJz_Ly8GqnbxuMI6_2IWa4wRqeeZVM4NFk6YbM@z>

here is a more thorough but still rudimentary fix to the eqn problem.
david hogan's fix solves the problem but doesn't address the issue.
as a side note, the textc() routine illustrates why plan 9 doesn't by
default use ansi's specification for multibyte and wide characters.

eqn% diff text.c /n/dump/1995/0401/sys/src/cmd/eqn
40,57d39
< int textc(void)	/* read next UTF rune from psp */
< {
< 	wchar_t r;
< 	int w;
< 
< 	w = mbtowc(&r, psp, 3);
< 	if(w == 0){
< 		psp++;
< 		return 0;
< 	}
< 	if(w < 0){
< 		psp += 1;
< 		return 0x80;	/* Plan 9-ism */
< 	}
< 	psp += w;
< 	return r;
< }
< 
92c74
< 		for (psp = p1; (c = textc()) != '\0'; ) {
---
> 		for (psp = p1; (c = *psp++) != '\0'; ) {
115,124d96
< int isalpharune(int c)
< {
< 	return ('a'<=c && c<='z') || ('A'<=c && c<='Z');
< }
< 
< int isdigitrune(int c)
< {
< 	return ('0'<=c && c<='9');
< }
< 
129c101
< 	if (isalpharune(c) && ft == ITAL && c != 'f' && c != 'j') {	/* italic letter */
---
> 	if (isalpha(c) && ft == ITAL && c != 'f' && c != 'j') {	/* italic letter */
134c106
< 	if (isalpharune(c) && ft != ITAL) {		/* other letter */
---
> 	if (isalpha(c) && ft != ITAL) {		/* other letter */
139c111
< 	if (isdigitrune(c)) {
---
> 	if (isdigit(c)) {
290c262
< void cadd(int c)		/* add character c to end of cs */
---
> void cadd(int c)		/* add char c to end of cs */
293d264
< 	int w;
315,317c286
< 	w = wctomb(csp, c);
< 	if(w > 0)	/* ignore bad characters */
< 		csp += w;
---
> 	*csp++ = c;