FUNCTION vector_difference

(* SCHEMA STRUCTURAL_FRAME_SCHEMA; *)

(* Modified for LPM/6 *)
FUNCTION vector_difference
	(arg1, arg2 : vector_or_direction) : vector;
   LOCAL
     result          : vector;
     res, vec1, vec2 : direction;
     mag, mag1, mag2 : REAL;
     ndim            : INTEGER;
   END_LOCAL;

   IF ((NOT EXISTS (arg1)) OR (NOT EXISTS (arg2))) OR (arg1.dim <> arg2.dim)
       THEN
     RETURN (?) ;
    ELSE
     BEGIN
       IF 'STRUCTURAL_FRAME_SCHEMA.VECTOR' IN TYPEOF(arg1) THEN
         mag1 := arg1.magnitude;
         vec1 := arg1.orientation;
       ELSE
         mag1 := 1.0;
         vec1 := arg1;
       END_IF;
       IF 'STRUCTURAL_FRAME_SCHEMA.VECTOR' IN TYPEOF(arg2) THEN
         mag2 := arg2.magnitude;
         vec2 := arg2.orientation;
       ELSE
         mag2 := 1.0;
         vec2 := arg2;
       END_IF;
       vec1 := normalise (vec1);
       vec2 := normalise (vec2);
       ndim := SIZEOF(vec1.direction_ratios);
       mag := 0.0;
       res := dummy_gri || direction(vec1.direction_ratios);
       REPEAT i := 1 TO ndim;
         res.direction_ratios[i] := mag1*vec1.direction_ratios[i] +
                                     mag2*vec2.direction_ratios[i];
         mag := mag + (res.direction_ratios[i]*res.direction_ratios[i]);
       END_REPEAT;
       IF (mag > 0.0 ) THEN
       result := dummy_gri || vector( res, SQRT(mag));
       ELSE
         result := dummy_gri || vector( vec1,  0.0);
       END_IF;
     END;
   END_IF;
   RETURN (result);
END_FUNCTION;  (*  STEP Part 42 (modified for 2nd edition)  *)

Referenced By

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2023-03-25T00:11:39-04:00