Let's try this. It's BUGGERED.
diff --git a/src/cmd/eqn/sqrt.c b/src/cmd/eqn/sqrt.c
new file mode 100644
index 0000000..391d924
--- /dev/null
+++ b/src/cmd/eqn/sqrt.c
@@ -0,0 +1,35 @@
+#include "e.h"
+
+void sqrt(int p2)
+{
+ static int af = 0;
+ int nps; /* point size for radical */
+ double radscale = 0.95;
+
+ if (ttype == DEVPOST)
+ radscale = 1.05;
+ nps = ps * radscale * eht[p2] / EM(1.0,ps) + 0.99; /* kludgy */
+ nps = max(EFFPS(nps), ps);
+ yyval = p2;
+ if (ttype == DEVCAT || ttype == DEVAPS)
+ eht[yyval] = EM(1.2, nps);
+ else if (ttype == DEVPOST)
+ eht[yyval] = EM(1.15, nps);
+ else /* DEV202, DEVPOST */
+ eht[yyval] = EM(1.15, nps);
+ dprintf(".\tS%d <- sqrt S%d;b=%g, h=%g, nps=%d\n",
+ yyval, p2, ebase[yyval], eht[yyval], nps);
+ printf(".as %d \\|\n", yyval);
+ nrwid(p2, ps, p2);
+ if (af++ == 0)
+ printf(".af 10 01\n"); /* make it two digits when it prints */
+ printf(".nr 10 %.3fu*\\n(.su/10\n", 9.2*eht[p2]); /* this nonsense */
+ /* guesses point size corresponding to height of stuff */
+ printf(".ds %d \\v'%gm'\\s(\\n(10", yyval, REL(ebase[p2],ps));
+ if (ttype == DEVCAT || ttype == DEVAPS)
+ printf("\\v'-.2m'\\(sr\\l'\\n(%du\\(rn'\\v'.2m'", p2);
+ else /* DEV202, DEVPOST so far */
+ printf("\\(sr\\l'\\n(%du\\(rn'", p2);
+ printf("\\s0\\v'%gm'\\h'-\\n(%du'\\^\\*(%d\n", REL(-ebase[p2],ps), p2, p2);
+ lfont[yyval] = rfont[yyval] = ROM;
+}
