diff --git a/calcerr.tbl b/calcerr.tbl
index 618d329..d22a2f2 100644
--- a/calcerr.tbl
+++ b/calcerr.tbl
@@ -1,7 +1,7 @@
 #
 # calcerr - error codes and messages
 #
-# Copyright (C) 1999-2006  Ernest Bowen
+# Copyright (C) 1999-2006,2021  Ernest Bowen
 #
 # Calc is open software; you can redistribute it and/or modify it under
 # the terms of the version 2.1 of the GNU Lesser General Public License
@@ -500,3 +500,7 @@ E_D2R1		Bad epsilon for converting degrees to radians
 E_D2R2		Bad first argument converting degrees to radians
 E_R2D1		Bad epsilon for converting radians to degrees
 E_R2D2		Bad first argument converting radians to degrees
+E_G2R1		Bad epsilon for converting gradians to radians
+E_G2R2		Bad first argument converting gradians to radians
+E_R2G1		Bad epsilon for converting radians to gradians
+E_R2G2		Bad first argument converting radians to gradians
diff --git a/func.c b/func.c
index 4cf2901..93dca01 100644
--- a/func.c
+++ b/func.c
@@ -2265,6 +2265,90 @@ f_r2d(int count, VALUE **vals)
 }
 
 
+/*
+ * f_d2r - convert gradians to radians
+ */
+S_FUNC VALUE
+f_g2r(int count, VALUE **vals)
+{
+	VALUE result;
+	NUMBER *eps;
+	NUMBER *pidiv200;
+
+	/* initialize VALUE */
+	result.v_subtype = V_NOSUBTYPE;
+
+	/* firewall */
+	eps = conf->epsilon;
+	if (count == 2) {
+		if (vals[1]->v_type != V_NUM || qiszero(vals[1]->v_num))
+			return error_value(E_G2R1);
+		eps = vals[1]->v_num;
+	}
+
+	/* calculate argument * (pi/200) */
+	switch (vals[0]->v_type) {
+		case V_NUM:
+			pidiv200 = qpidiv200(eps);
+			result.v_num = qmul(vals[0]->v_num, pidiv200);
+			result.v_type = V_NUM;
+			qfree(pidiv200);
+			break;
+		case V_COM:
+			pidiv200 = qpidiv200(eps);
+			result.v_com = c_mulq(vals[0]->v_com, pidiv200);
+			result.v_type = V_COM;
+			qfree(pidiv200);
+			break;
+		default:
+			return error_value(E_G2R2);
+	}
+	return result;
+}
+
+
+/*
+ * f_r2g - convert radians to gradians
+ */
+S_FUNC VALUE
+f_r2g(int count, VALUE **vals)
+{
+	VALUE result;
+	NUMBER *eps;
+	NUMBER *pidiv200;
+
+	/* initialize VALUE */
+	result.v_subtype = V_NOSUBTYPE;
+
+	/* firewall */
+	eps = conf->epsilon;
+	if (count == 2) {
+		if (vals[1]->v_type != V_NUM || qiszero(vals[1]->v_num))
+			return error_value(E_R2G1);
+		eps = vals[1]->v_num;
+	}
+
+	/* calculate argument / (pi/200) */
+	switch (vals[0]->v_type) {
+		case V_NUM:
+			pidiv200 = qpidiv200(eps);
+			result.v_num = qqdiv(vals[0]->v_num, pidiv200);
+			result.v_type = V_NUM;
+			qfree(pidiv200);
+			break;
+		case V_COM:
+			pidiv200 = qpidiv200(eps);
+			result.v_com = c_divq(vals[0]->v_com, pidiv200);
+			result.v_type = V_COM;
+			qfree(pidiv200);
+			break;
+		default:
+			return error_value(E_R2G2);
+	}
+	return result;
+}
+
+
 S_FUNC VALUE
 f_sin(int count, VALUE **vals)
 {
@@ -8866,6 +8950,8 @@ STATIC CONST struct builtin builtins[] = {
 	 "return the file position"},
 	{"frac", 1, 1, 0, OP_FRAC, qfrac, 0,
 	 "fractional part of value"},
+	{"g2r", 1, 2, 0, OP_NOP, 0, f_g2r,
+	 "convert gradians to radians"},
 	{"gcd", 1, IN, 0, OP_NOP, f_gcd, 0,
 	 "greatest common divisor"},
 	{"gcdrem", 2, 2, 0, OP_NOP, qgcdrem, 0,
@@ -9115,6 +9201,8 @@ STATIC CONST struct builtin builtins[] = {
 	 "\t\t\tdivided by b"},
 	{"r2d", 1, 2, 0, OP_NOP, 0, f_r2d,
 	 "convert radians to degrees"},
+	{"r2g", 1, 2, 0, OP_NOP, 0, f_r2g,
+	 "convert radians to gradians"},
 	{"rand", 0, 2, 0, OP_NOP, f_rand, 0,
 	 "additive 55 random number [0,2^64), [0,a), or [a,b)"},
 	{"randbit", 0, 1, 0, OP_NOP, f_randbit, 0,
diff --git a/qmath.h b/qmath.h
index b36a37c..f19f4d6 100644
--- a/qmath.h
+++ b/qmath.h
@@ -1,7 +1,7 @@
 /*
  * qmath - declarations for extended precision rational arithmetic
  *
- * Copyright (C) 1999-2007,2014  David I. Bell
+ * Copyright (C) 1999-2007,2014,2021  David I. Bell
  *
  * Calc is open software; you can redistribute it and/or modify it under
  * the terms of the version 2.1 of the GNU Lesser General Public License
@@ -214,6 +214,7 @@ E_FUNC NUMBER *qacoth(NUMBER *q, NUMBER *epsilon);
 E_FUNC NUMBER *qlegtoleg(NUMBER *q, NUMBER *epsilon, BOOL wantneg);
 E_FUNC NUMBER *qpi(NUMBER *epsilon);
 E_FUNC NUMBER *qpidiv180(NUMBER *epsilon);
+E_FUNC NUMBER *qpidiv200(NUMBER *epsilon);
 E_FUNC NUMBER *qcatalan(NUMBER *);
 E_FUNC NUMBER *qbern(ZVALUE z);
 E_FUNC void qfreebern(void);
diff --git a/qtrans.c b/qtrans.c
index 926facc..2da35ac 100644
--- a/qtrans.c
+++ b/qtrans.c
@@ -56,12 +56,17 @@ STATIC NUMBER *ln_10_epsilon = NULL;
  * pivalue[LAST_PI_DIV_180_EPSILON] - last epsilon used to calculate pi/180
  * pivalue[LAST_PI_DIV_180_VALUE] - last calculated pi/180 given
  *				      pivalue[LAST_PI_DIV_180_EPSILON] epsilon
+ * pivalue[LAST_PI_DIV_200_EPSILON] - last epsilon used to calculate pi/200
+ * pivalue[LAST_PI_DIV_200_VALUE] - last calculated pi/200 given
+ *				      pivalue[LAST_PI_DIV_200_EPSILON] epsilon
  */
 enum pi_cache {
 	LAST_PI_EPSILON = 0,
 	LAST_PI_VALUE,
 	LAST_PI_DIV_180_EPSILON,
 	LAST_PI_DIV_180_VALUE,
+	LAST_PI_DIV_200_EPSILON,
+	LAST_PI_DIV_200_VALUE,
 	PI_CACHE_LEN	/* must be last */
 };
 STATIC NUMBER *pivalue[PI_CACHE_LEN] = {
@@ -69,6 +74,8 @@ STATIC NUMBER *pivalue[PI_CACHE_LEN] = {
 	NULL,	/* LAST_PI_VALUE */
 	NULL,	/* LAST_PI_DIV_180_EPSILON */
 	NULL,	/* LAST_PI_DIV_180_VALUE */
+	NULL,	/* LAST_PI_DIV_200_EPSILON */
+	NULL,	/* LAST_PI_DIV_200_VALUE */
 };
 
 /*
@@ -812,7 +819,7 @@ qpi(NUMBER *epsilon)
 /*
  * qpidiv180 - calcucalte pi / 180
  *
- * This function returns pi/180 as used to covert between degrees and radians.
+ * This function returns pi/180 as used to covert between radians and degrees.
  */
 NUMBER *
 qpidiv180(NUMBER *epsilon)
@@ -853,6 +860,50 @@ qpidiv180(NUMBER *epsilon)
 }
 
 
+/*
+ * qpidiv200 - calcucalte pi / 200
+ *
+ * This function returns pi/200 as used to covert between radians and gradians.
+ */
+NUMBER *
+qpidiv200(NUMBER *epsilon)
+{
+	NUMBER *pi, *pidiv200;
+
+	/* firewall */
+	if (qiszero(epsilon)) {
+		math_error("zero epsilon value for qpidiv200");
+		/*NOTREACHED*/
+	}
+
+	/* use pi/200 cache if epsilon marches, else flush if needed */
+	if (pivalue[LAST_PI_DIV_200_EPSILON] != NULL &&
+	    pivalue[LAST_PI_DIV_200_VALUE] != NULL &&
+	    epsilon == pivalue[LAST_PI_DIV_200_EPSILON]) {
+		return qlink(pivalue[LAST_PI_DIV_200_VALUE]);
+	}
+	if (pivalue[LAST_PI_DIV_200_EPSILON] != NULL) {
+		qfree(pivalue[LAST_PI_DIV_200_EPSILON]);
+	}
+	if (pivalue[LAST_PI_DIV_200_VALUE] != NULL) {
+		qfree(pivalue[LAST_PI_DIV_200_VALUE]);
+	}
+
+	/* let qpi() returned cached pi or calculate new as needed */
+	pi = qpi(epsilon);
+
+	/* calculate pi/200 */
+	pidiv200 = qdivi(pi, 200);
+
+	/* cache epsilon and pi/200 */
+	pivalue[LAST_PI_DIV_200_EPSILON] = qlink(epsilon);
+	pivalue[LAST_PI_DIV_200_VALUE] = qlink(pidiv200);
+
+	/* return pi/200 */
+	return pidiv200;
+}
+
+
 /*
  * Calculate the exponential function to the nearest or next to nearest
  * multiple of the positive number epsilon.