PR: Add meshgrid (#145)

Author: steff456

Diff for: spec/API_specification/creation_functions.md

@@ -289,6 +289,37 @@ Returns evenly spaced numbers over a specified interval.
 
     -   a one-dimensional array containing evenly spaced values.
 
+(function-meshgrid)=
+### meshgrid(*arrays, /, *, indexing='xy')
+
+Returns coordinate matrices from coordinate vectors.
+
+#### Parameters
+
+-    **arrays**: _Sequence\[ <array> ]_
+
+     -   one-dimensional arrays representing grid coordinates. Must have a numeric data type.
+
+-    **indexing**: _str_
+
+    -   Cartesian 'xy' or matrix 'ij' indexing of output. If provided zero or one one-dimensional vector(s) (i.e., the zero- and one-dimensional cases, respectively), the `indexing` keyword has no effect and should be ignored. Default: `'xy'`.
+
+#### Returns
+
+-    **out**: _List\[ <array>, ... ]_
+
+    -   list of N arrays, where `N` is the number of provided one-dimensional input arrays. Each returned array must have rank `N`. For `N` one-dimensional arrays having lengths `Ni = len(xi)`,
+
+        -   if matrix indexing `ij`, then each returned array must have the shape `(N1, N2, N3, ..., Nn)`.
+
+        -   if Cartesian indexing `xy`, then each returned array must have shape `(N2, N1, N3, ..., Nn)`.
+
+        Accordingly, for the two-dimensional case with input one-dimensional arrays of length `M` and `N`, if matrix indexing `ij`, then each returned array must have shape `(M, N)`, and, if Cartesian indexing `xy`, then each returned array must have shape `(N, M)`.
+
+        Similarly, for the three-dimensional case with input one-dimensional arrays of length `M`, `N`, and `P`, if matrix indexing `ij`, then each returned array must have shape `(M, N, P)`, and, if Cartesian indexing `xy`, then each returned array must have shape `(N, M, P)`.
+
+        The returned arrays must have a numeric data type determined by {ref}`type-promotion`.
+
 (function-ones)=
 ### ones(shape, /, *, dtype=None, device=None)