COMMENT ⊗   VALID 00002 PAGES
C REC  PAGE   DESCRIPTION
C00001 00001
C00002 00002	BEGIN "EX4"
C00004 ENDMK
C⊗;
BEGIN "EX4"
	REQUIRE "GEOMES.HDR[GEM,HE]" SOURCE_FILE;
	DEFINE αα="COMMENT";
	DEFINE π="3.1415927";
INTEGER PROCEDURE MKTETRA (REAL R);
BEGIN "MKTETRA"
	INTEGER B,F1,F2,V1,V2,V3,V4;
	B ← MKBFV; F1 ← PFACE(B); V1 ← PVT(B);		αα MAKE POINT POLYHDERA;
	XWC(V1) ← ABS(R*0.942809); ZWC(V1) ← -ABS(R/3);	αα POSITION FIRST VERTEX;
	V2 ← MKEV(F1,V1); ROTATE(V2,0,0,2*π/3);		αα MAKE AND POSITION 2ND VERTEX;
	V3 ← MKEV(F1,V2); ROTATE(V3,0,0,2*π/3);		αα MAKE AND POSITION 3RD VERTEX;
	V4 ← MKEV(F1,V3);				αα MAKE AND POSITION 4TH VERTEX;
	XWC(V4)←YWC(V4)←0;ZWC(V4)←ABS(R);
	MKFE(V1,F1,V4); F2 ← PFACE(F1);
	MKFE(V1,F1,V3);	MKFE(V2,F2,V4);
	RETURN(B);
END "MKTETRA";
	MKUNIV;
	MKTETRA(6);
	GEODPY; INCHRW;
END "EX4";