QGIS/resources/function_help/json/straight_distance_2d

{
  "name": "straight_distance_2d",
  "type": "function",
  "groups": ["GeometryGroup"],
  "description": "Returns the direct/euclidean distance between the first and last vertex of a geometry. The geometry must be a curve (circularstring, linestring).",
  "arguments": [
    {"arg":"geometry", "description": "The geometry."}
  ],
  "examples": [
    { "expression":"straight_distance_2d(geom_from_wkt('LINESTRING(1 0, 1 1)'))", "returns":"1"},
    { "expression":"round(straight_distance_2d(geom_from_wkt('LINESTRING(1 4, 3 5, 5 0)')), 3)", "returns":"5.657"}
  ]
}