perlin: document name param, float-dtype requirement, and ValueError

.claude/sweep-documentation-state.csv

@@ -0,0 +1,2 @@
+module,last_inspected,issue,severity_max,categories_found,notes,doc_coverage
+perlin,2026-06-23,,MEDIUM,2;5,"name param undocumented (Cat2) + float-dtype requirement/ValueError undocumented, no Raises section (Cat5); fixed in deep-sweep-documentation-perlin-2026-06-23; repo has issues disabled so no issue number; example runs and output matches; 1 public func (perlin) listed in reference/surface.rst",1/1

xrspatial/perlin.py

@@ -294,16 +294,28 @@ def perlin(agg: xr.DataArray,
     agg : xr.DataArray
         2D array of size width x height, will be used to determine
         height/ width and which platform to use for calculation.
+        Must have a floating-point dtype (float32 or float64); integer
+        input is rejected (see Raises).
     freq : tuple, default=(1,1)
         (x, y) frequency multipliers.
     seed : int, default=5
         Seed for random number generator.
+    name : str, default='perlin'
+        Name assigned to the output DataArray.
 
     Returns
     -------
     perlin_agg : xarray.DataArray
         2D array of perlin noise values.
 
+    Raises
+    ------
+    ValueError
+        If `agg` does not have a floating-point dtype. The noise is
+        written into `agg` in place and then normalized; an integer
+        buffer would truncate the float values to zero and corrupt the
+        result, so non-float input is rejected up front.
+
     References
     ----------
         - Paul Panzer: https://stackoverflow.com/questions/42147776/producing-2d-perlin-noise-with-numpy # noqa