COMMENT ⊗   VALID 00002 PAGES
C REC  PAGE   DESCRIPTION
C00001 00001	   VALID 00007 PAGES
C00002 00002	BEGIN "TENSOR"
C00010 ENDMK
C⊗;
BEGIN "TENSOR"
	REQUIRE "ABBREV[SYS,BGB]" SOURCE_FILE;
	REQUIRE "DPYIII[SYS,BGB]" SOURCE_FILE;
	REQUIRE "SAITRG[SYS,BGB]" SOURCE_FILE;
	SAFE ITG ARRAY DPYBUF[0:500];
	REAL X0,Y0,DX,DY,X1,Y1,X2,Y2,R,C,S;
	X0 ← Y0 ← 250;
	C ← COS(π/8); S ← SIN(π/8);
WHILE TRUE DO
BEGIN "LOOP"
	DPYSET(DPYBUF);
	AIVECT(-511,-511);
	AVECT(+511,-511);
	AVECT(+511,+511);
	AVECT(-511,+511);
	AVECT(-511,-511);
	X0 ← X0 - Y0*0.01;
	Y0 ← Y0 + X0*0.01;
! COMPUTE ARROW HEAD COORDINATES;
	DX ← -X0;
	DY ← -Y0;
	R  ← SQRT(DX*DX + DY*DY);
	DX ← DX/R;
	DY ← DY/R;
	X2 ← X0 + 150*(C*DX - S*DY); Y2 ← Y0 + 150*(C*DY + S*DX);
	X1 ← X0 + 150*(C*DX + S*DY); Y1 ← Y0 + 150*(C*DY - S*DX);
	AIVECT(0,0);
	AVECT(X0,Y0);
	AVECT(X1,Y1);
	AVECT(X2,Y2);
	AVECT(X0,Y0);
	DPYOUT(1);
END "LOOP";
END "TENSOR";