We can consider geometry and a float value as the inputs, and we want the function to return geometry:

CREATE OR REPLACE FUNCTION chp04.create_grid (geometry, float) RETURNS geometry AS $$ 

In order to construct the subplots, we will require three lines running parallel to the X axis:

WITH middleline AS ( 
  SELECT ST_MakeLine(ST_Translate($1, -10, 0), 
    ST_Translate($1, 40.0, 0)) AS the_geom 
), 
topline AS ( 
  SELECT ST_MakeLine(ST_Translate($1, -10, 10.0),
    ST_Translate($1, 40.0, 10)) AS the_geom 
), 
bottomline AS ( 
  SELECT ST_MakeLine(ST_Translate($1, -10, -10.0), 
    ST_Translate($1, 40.0, -10)) AS the_geom 
),

And we will require six lines running parallel to the Y axis:

oneline AS ( 
  SELECT ST_MakeLine(ST_Translate($1, -10, 10.0), 
    ST_Translate($1, -10, -10)) AS the_geom 
), 
twoline AS ( 
  SELECT ST_MakeLine(ST_Translate($1, 0, 10.0),
    ST_Translate($1, 0, -10)) AS the_geom 
), 
threeline AS ( 
  SELECT ST_MakeLine(ST_Translate($1, 10, 10.0),
    ST_Translate($1, 10, -10)) AS the_geom 
), 
fourline AS ( 
  SELECT ST_MakeLine(ST_Translate($1, 20, 10.0),
    ST_Translate($1, 20, -10)) AS the_geom 
), 
fiveline AS ( 
  SELECT ST_MakeLine(ST_Translate($1, 30, 10.0),
    ST_Translate($1, 30, -10)) AS the_geom 
), 
sixline AS ( 
  SELECT ST_MakeLine(ST_Translate($1, 40, 10.0), 
    ST_Translate($1, 40, -10)) AS the_geom 
), 

To use these for polygon construction, we will require them to have nodes where they cross and touch. A UNION ALL function will combine these lines in a single record; ST_Union will provide the geometric processing necessary to construct the nodes of interest and will combine our lines into a single entity ready for chp04.polygonize_to_multi:

combined AS ( 
  SELECT ST_Union(the_geom) AS the_geom FROM 
  ( 
    SELECT the_geom FROM middleline 
      UNION ALL 
    SELECT the_geom FROM topline 
      UNION ALL 
    SELECT the_geom FROM bottomline 
      UNION ALL 
    SELECT the_geom FROM oneline 
      UNION ALL 
    SELECT the_geom FROM twoline 
      UNION ALL 
    SELECT the_geom FROM threeline 
      UNION ALL 
    SELECT the_geom FROM fourline 
      UNION ALL 
    SELECT the_geom FROM fiveline 
      UNION ALL 
    SELECT the_geom FROM sixline 
  ) AS alllines 
) 

But we have not created polygons yet, just lines. The final step, using our polygonize_to_multi function, finishes the work for us:

SELECT chp04.polygonize_to_multi(ST_Rotate(the_geom, $2, $1)) AS the_geom FROM combined; 

The combined query is as follows:

CREATE OR REPLACE FUNCTION chp04.create_grid (geometry, float) RETURNS geometry AS $$ 
 
WITH middleline AS ( 
  SELECT ST_MakeLine(ST_Translate($1, -10, 0),
    ST_Translate($1, 40.0, 0)) AS the_geom 
), 
topline AS ( 
  SELECT ST_MakeLine(ST_Translate($1, -10, 10.0),
    ST_Translate($1, 40.0, 10)) AS the_geom 
), 
bottomline AS ( 
  SELECT ST_MakeLine(ST_Translate($1, -10, -10.0), 
    ST_Translate($1, 40.0, -10)) AS the_geom 
), 
oneline AS ( 
  SELECT ST_MakeLine(ST_Translate($1, -10, 10.0),
    ST_Translate($1, -10, -10)) AS the_geom 
), 
twoline AS ( 
  SELECT ST_MakeLine(ST_Translate($1, 0, 10.0),
    ST_Translate($1, 0, -10)) AS the_geom 
), 
threeline AS ( 
  SELECT ST_MakeLine(ST_Translate($1, 10, 10.0), 
    ST_Translate($1, 10, -10)) AS the_geom 
), 
fourline AS ( 
  SELECT ST_MakeLine(ST_Translate($1, 20, 10.0),
    ST_Translate($1, 20, -10)) AS the_geom 
), 
fiveline AS ( 
  SELECT ST_MakeLine(ST_Translate($1, 30, 10.0),
    ST_Translate($1, 30, -10)) AS the_geom 
), 
sixline AS ( 
  SELECT ST_MakeLine(ST_Translate($1, 40, 10.0),
    ST_Translate($1, 40, -10)) AS the_geom 
), 
combined AS ( 
  SELECT ST_Union(the_geom) AS the_geom FROM 
  ( 
    SELECT the_geom FROM middleline 
      UNION ALL 
    SELECT the_geom FROM topline 
      UNION ALL 
    SELECT the_geom FROM bottomline 
      UNION ALL 
    SELECT the_geom FROM oneline 
      UNION ALL 
    SELECT the_geom FROM twoline 
      UNION ALL 
    SELECT the_geom FROM threeline 
      UNION ALL 
    SELECT the_geom FROM fourline 
      UNION ALL 
    SELECT the_geom FROM fiveline 
      UNION ALL 
    SELECT the_geom FROM sixline 
  ) AS alllines 
) 
SELECT chp04.polygonize_to_multi(ST_Rotate(the_geom, $2, $1)) AS the_geom FROM combined; 
$$ LANGUAGE SQL;