Operator
Description
Example(s)
| | | | | | | | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------------------------------------------------------------------------- | -------------------------------------------------- | --------------------------------------------------------------------------------------------------------------- | - | -------------------------------------------------- | |geometric\_type + point → geometric\_type
Adds the coordinates of the second point to those of each point of the first argument, thus performing translation. Available for point, box, path, circle.
box '(1,1),(0,0)' + point '(2,0)' → (3,1),(2,0)
path + path → path
Concatenates two open paths (returns NULL if either path is closed).
path '\[(0,0),(1,1)]' + path '\[(2,2),(3,3),(4,4)]' → \[(0,0),(1,1),(2,2),(3,3),(4,4)]
geometric\_type - point → geometric\_type
Subtracts the coordinates of the second point from those of each point of the first argument, thus performing translation. Available for point, box, path, circle.
box '(1,1),(0,0)' - point '(2,0)' → (-1,1),(-2,0)
geometric\_type \* point → geometric\_type
Multiplies each point of the first argument by the second point (treating a point as being a complex number represented by real and imaginary parts, and performing standard complex multiplication). If one interprets the second point as a vector, this is equivalent to scaling the object's size and distance from the origin by the length of the vector, and rotating it counterclockwise around the origin by the vector's angle from the x axis. Available for point, box,\[a] path, circle.
path '((0,0),(1,0),(1,1))' \* point '(3.0,0)' → ((0,0),(3,0),(3,3))
path '((0,0),(1,0),(1,1))' \* point(cosd(45), sind(45)) → ((0,0),(0.7071067811865475,0.7071067811865475),(0,1.414213562373095))
geometric\_type / point → geometric\_type
Divides each point of the first argument by the second point (treating a point as being a complex number represented by real and imaginary parts, and performing standard complex division). If one interprets the second point as a vector, this is equivalent to scaling the object's size and distance from the origin down by the length of the vector, and rotating it clockwise around the origin by the vector's angle from the x axis. Available for point, box,\[a] path, circle.
path '((0,0),(1,0),(1,1))' / point '(2.0,0)' → ((0,0),(0.5,0),(0.5,0.5))
path '((0,0),(1,0),(1,1))' / point(cosd(45), sind(45)) → ((0,0),(0.7071067811865476,-0.7071067811865476),(1.4142135623730951,0))
@-@ geometric\_type → double precision
Computes the total length. Available for lseg, path.
@-@ path '\[(0,0),(1,0),(1,1)]' → 2
@@ geometric\_type → point
Computes the center point. Available for box, lseg, polygon, circle.
@@ box '(2,2),(0,0)' → (1,1)
# geometric\_type → integer
Returns the number of points. Available for path, polygon.
# path '((1,0),(0,1),(-1,0))' → 3
geometric\_type # geometric\_type → point
Computes the point of intersection, or NULL if there is none. Available for lseg, line.
lseg '\[(0,0),(1,1)]' # lseg '\[(1,0),(0,1)]' → (0.5,0.5)
box # box → box
Computes the intersection of two boxes, or NULL if there is none.
box '(2,2),(-1,-1)' # box '(1,1),(-2,-2)' → (1,1),(-1,-1)
geometric\_type ## geometric\_type → point
Computes the closest point to the first object on the second object. Available for these pairs of types: (point, box), (point, lseg), (point, line), (lseg, box), (lseg, lseg), (line, lseg).
point '(0,0)' ## lseg '\[(2,0),(0,2)]' → (1,1)
geometric\_type <-> geometric\_type → double precision
Computes the distance between the objects. Available for all seven geometric types, for all combinations of point with another geometric type, and for these additional pairs of types: (box, lseg), (lseg, line), (polygon, circle) (and the commutator cases).
circle '<(0,0),1>' <-> circle '<(5,0),1>' → 3
geometric\_type @> geometric\_type → boolean
Does first object contain second? Available for these pairs of types: (box, point), (box, box), (path, point), (polygon, point), (polygon, polygon), (circle, point), (circle, circle).
circle '<(0,0),2>' @> point '(1,1)' → t
geometric\_type <@ geometric\_type → boolean
Is first object contained in or on second? Available for these pairs of types: (point, box), (point, lseg), (point, line), (point, path), (point, polygon), (point, circle), (box, box), (lseg, box), (lseg, line), (polygon, polygon), (circle, circle).
point '(1,1)' <@ circle '<(0,0),2>' → t
geometric\_type && geometric\_type → boolean
Do these objects overlap? (One point in common makes this true.) Available for box, polygon, circle.
box '(1,1),(0,0)' && box '(2,2),(0,0)' → t
geometric\_type << geometric\_type → boolean
Is first object strictly left of second? Available for point, box, polygon, circle.
circle '<(0,0),1>' << circle '<(5,0),1>' → t
geometric\_type >> geometric\_type → boolean
Is first object strictly right of second? Available for point, box, polygon, circle.
circle '<(5,0),1>' >> circle '<(0,0),1>' → t
geometric\_type &< geometric\_type → boolean
Does first object not extend to the right of second? Available for box, polygon, circle.
box '(1,1),(0,0)' &< box '(2,2),(0,0)' → t
geometric\_type &> geometric\_type → boolean
Does first object not extend to the left of second? Available for box, polygon, circle.
box '(3,3),(0,0)' &> box '(2,2),(0,0)' → t
geometric\_type << | geometric\_type → boolean
Is first object strictly below second? Available for point, box, polygon, circle.
box '(3,3),(0,0)' << | box '(5,5),(3,4)' → t
geometric\_type | >> geometric\_type → boolean
Is first object strictly above second? Available for point, box, polygon, circle.
box '(5,5),(3,4)' | >> box '(3,3),(0,0)' → t
geometric\_type &< | geometric\_type → boolean
Does first object not extend above second? Available for box, polygon, circle.
box '(1,1),(0,0)' &< | box '(2,2),(0,0)' → t
geometric\_type | &> geometric\_type → boolean
Does first object not extend below second? Available for box, polygon, circle.
box '(3,3),(0,0)' | &> box '(2,2),(0,0)' → t
box <^ box → boolean
Is first object below second (allows edges to touch)?
box '((1,1),(0,0))' <^ box '((2,2),(1,1))' → t
box >^ box → boolean
Is first object above second (allows edges to touch)?
box '((2,2),(1,1))' >^ box '((1,1),(0,0))' → t
geometric\_type ?# geometric\_type → boolean
Do these objects intersect? Available for these pairs of types: (box, box), (lseg, box), (lseg, lseg), (lseg, line), (line, box), (line, line), (path, path).
lseg '\[(-1,0),(1,0)]' ?# box '(2,2),(-2,-2)' → t
?- line → boolean
?- lseg → boolean
Is line horizontal?
?- lseg '\[(-1,0),(1,0)]' → t
point ?- point → boolean
Are points horizontally aligned (that is, have same y coordinate)?
point '(1,0)' ?- point '(0,0)' → t
? | line → boolean
? | lseg → boolean
Is line vertical?
? | lseg '\[(-1,0),(1,0)]' → f
point ? | point → boolean
Are points vertically aligned (that is, have same x coordinate)?
point '(0,1)' ? | point '(0,0)' → t
line ?- | line → boolean
lseg ?- | lseg → boolean
Are lines perpendicular?
lseg '\[(0,0),(0,1)]' ?- | lseg '\[(0,0),(1,0)]' → t
line ? | | line → boolean
lseg ? | | lseg → boolean
Are lines parallel?
lseg '\[(-1,0),(1,0)]' ? | | lseg '\[(-1,2),(1,2)]' → t
geometric\_type \~= geometric\_type → boolean
Are these objects the same? Available for point, box, polygon, circle.
polygon '((0,0),(1,1))' \~= polygon '((1,1),(0,0))' → t
Function
Description
Example(s)
| | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | |area ( geometric\_type ) → double precision
Computes area. Available for box, path, circle. A path input must be closed, else NULL is returned. Also, if the path is self-intersecting, the result may be meaningless.
area(box '(2,2),(0,0)') → 4
center ( geometric\_type ) → point
Computes center point. Available for box, circle.
center(box '(1,2),(0,0)') → (0.5,1)
diagonal ( box ) → lseg
Extracts box's diagonal as a line segment (same as lseg(box)).
diagonal(box '(1,2),(0,0)') → \[(1,2),(0,0)]
diameter ( circle ) → double precision
Computes diameter of circle.
diameter(circle '<(0,0),2>') → 4
height ( box ) → double precision
Computes vertical size of box.
height(box '(1,2),(0,0)') → 2
isclosed ( path ) → boolean
Is path closed?
isclosed(path '((0,0),(1,1),(2,0))') → t
isopen ( path ) → boolean
Is path open?
isopen(path '\[(0,0),(1,1),(2,0)]') → t
length ( geometric\_type ) → double precision
Computes the total length. Available for lseg, path.
length(path '((-1,0),(1,0))') → 4
npoints ( geometric\_type ) → integer
Returns the number of points. Available for path, polygon.
npoints(path '\[(0,0),(1,1),(2,0)]') → 3
pclose ( path ) → path
Converts path to closed form.
pclose(path '\[(0,0),(1,1),(2,0)]') → ((0,0),(1,1),(2,0))
popen ( path ) → path
Converts path to open form.
popen(path '((0,0),(1,1),(2,0))') → \[(0,0),(1,1),(2,0)]
radius ( circle ) → double precision
Computes radius of circle.
radius(circle '<(0,0),2>') → 2
slope ( point, point ) → double precision
Computes slope of a line drawn through the two points.
slope(point '(0,0)', point '(2,1)') → 0.5
width ( box ) → double precision
Computes horizontal size of box.
width(box '(1,2),(0,0)') → 1
Function
Description
Example(s)
| | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | |box ( circle ) → box
Computes box inscribed within the circle.
box(circle '<(0,0),2>') → (1.414213562373095,1.414213562373095),(-1.414213562373095,-1.414213562373095)
box ( point ) → box
Converts point to empty box.
box(point '(1,0)') → (1,0),(1,0)
box ( point, point ) → box
Converts any two corner points to box.
box(point '(0,1)', point '(1,0)') → (1,1),(0,0)
box ( polygon ) → box
Computes bounding box of polygon.
box(polygon '((0,0),(1,1),(2,0))') → (2,1),(0,0)
bound\_box ( box, box ) → box
Computes bounding box of two boxes.
bound\_box(box '(1,1),(0,0)', box '(4,4),(3,3)') → (4,4),(0,0)
circle ( box ) → circle
Computes smallest circle enclosing box.
circle(box '(1,1),(0,0)') → <(0.5,0.5),0.7071067811865476>
circle ( point, double precision ) → circle
Constructs circle from center and radius.
circle(point '(0,0)', 2.0) → <(0,0),2>
circle ( polygon ) → circle
Converts polygon to circle. The circle's center is the mean of the positions of the polygon's points, and the radius is the average distance of the polygon's points from that center.
circle(polygon '((0,0),(1,3),(2,0))') → <(1,1),1.6094757082487299>
line ( point, point ) → line
Converts two points to the line through them.
line(point '(-1,0)', point '(1,0)') → {0,-1,0}
lseg ( box ) → lseg
Extracts box's diagonal as a line segment.
lseg(box '(1,0),(-1,0)') → \[(1,0),(-1,0)]
lseg ( point, point ) → lseg
Constructs line segment from two endpoints.
lseg(point '(-1,0)', point '(1,0)') → \[(-1,0),(1,0)]
path ( polygon ) → path
Converts polygon to a closed path with the same list of points.
path(polygon '((0,0),(1,1),(2,0))') → ((0,0),(1,1),(2,0))
point ( double precision, double precision ) → point
Constructs point from its coordinates.
point(23.4, -44.5) → (23.4,-44.5)
point ( box ) → point
Computes center of box.
point(box '(1,0),(-1,0)') → (0,0)
point ( circle ) → point
Computes center of circle.
point(circle '<(0,0),2>') → (0,0)
point ( lseg ) → point
Computes center of line segment.
point(lseg '\[(-1,0),(1,0)]') → (0,0)
point ( polygon ) → point
Computes center of polygon (the mean of the positions of the polygon's points).
point(polygon '((0,0),(1,1),(2,0))') → (1,0.3333333333333333)
polygon ( box ) → polygon
Converts box to a 4-point polygon.
polygon(box '(1,1),(0,0)') → ((0,0),(0,1),(1,1),(1,0))
polygon ( circle ) → polygon
Converts circle to a 12-point polygon.
polygon(circle '<(0,0),2>') → ((-2,0),(-1.7320508075688774,0.9999999999999999),(-1.0000000000000002,1.7320508075688772),(-1.2246063538223773e-16,2),(0.9999999999999996,1.7320508075688774),(1.732050807568877,1.0000000000000007),(2,2.4492127076447545e-16),(1.7320508075688776,-0.9999999999999994),(1.0000000000000009,-1.7320508075688767),(3.673819061467132e-16,-2),(-0.9999999999999987,-1.732050807568878),(-1.7320508075688767,-1.0000000000000009))
polygon ( integer, circle ) → polygon
Converts circle to an n-point polygon.
polygon(4, circle '<(3,0),1>') → ((2,0),(3,1),(4,1.2246063538223773e-16),(3,-1))
polygon ( path ) → polygon
Converts closed path to a polygon with the same list of points.
polygon(path '((0,0),(1,1),(2,0))') → ((0,0),(1,1),(2,0))