Fix dtypes for qr (#594)

Author: tomwhite

cubed/array_api/linalg.py

@@ -4,6 +4,7 @@
 
 # These functions are in both the main and linalg namespaces
 from cubed.array_api.data_type_functions import result_type
+from cubed.array_api.dtypes import _floating_dtypes
 from cubed.array_api.linear_algebra_functions import (  # noqa: F401
     matmul,
     matrix_transpose,
@@ -33,6 +34,9 @@ def qr(x, /, *, mode="reduced") -> QRResult:
     if mode != "reduced":
         raise ValueError("qr only supports mode='reduced'")
 
+    if x.dtype not in _floating_dtypes:
+        raise TypeError("Only floating-point dtypes are allowed in qr")
+
     if x.numblocks[1] > 1:
         raise ValueError(
             "qr only supports tall-and-skinny (single column chunk) arrays. "
@@ -80,7 +84,7 @@ def _qr_first_step(A):
         nxp.linalg.qr,
         A,
         shapes=[A.shape, R1_shape],
-        dtypes=[nxp.float64, nxp.float64],
+        dtypes=[A.dtype, A.dtype],
         chunkss=[A.chunks, R1_chunks],
         extra_projected_mem=extra_projected_mem,
     )
@@ -119,7 +123,7 @@ def _qr_second_step(R1):
         nxp.linalg.qr,
         R1_single,
         shapes=[Q2_shape, R2_shape],
-        dtypes=[nxp.float64, nxp.float64],
+        dtypes=[R1.dtype, R1.dtype],
         chunkss=[Q2_chunks, R2_chunks],
         extra_projected_mem=extra_projected_mem,
     )
@@ -148,7 +152,7 @@ def _qr_third_step(Q1, Q2):
         Q1,
         Q2,
         shape=Q1_shape,
-        dtype=nxp.float64,
+        dtype=result_type(Q1, Q2),
         chunks=Q1_chunks,
         extra_projected_mem=extra_projected_mem,
         q1_chunks=Q1_chunks,