ST_NurbsCurveIsRational — Checks if a NURBS curve is rational (has weights).
boolean ST_NurbsCurveIsRational(geometry nurbscurve);
Returns TRUE if the NURBS curve has weights assigned to its control points (rational NURBS), FALSE if it uses uniform weights (non-rational B-spline).
Rational NURBS curves provide more flexibility in curve shape control through variable weights. Non-rational B-splines use uniform weights and are a special case of NURBS curves.
Raises an error if the input is not a NURBS curve. Returns NULL if the input is NULL.
Availability: 3.7.0
-- Check if a curve is rational
SELECT ST_NurbsCurveIsRational(ST_MakeNurbsCurve(2, 'LINESTRING(0 0, 5 10, 10 0)'::geometry,
ARRAY[1.0, 2.0, 1.0]));
-- Result: true
-- Non-rational curve
SELECT ST_NurbsCurveIsRational('NURBSCURVE(2, (0 0, 5 10, 10 0))'::geometry);
-- Result: false