This is the release note of v4.2.0. See here for the complete list of solved issues and merged PRs.

Highlights

Allocation strategy of pinned memory has been improved to reduce host memory usage.
Fixed bugs in multiple functions with arrays with complex dtypes.

Enhancements

Use cuDNN v7 APIs to get conv algos for TensorCore (#1134)
Fix cupy.diag failures for array-likes objects other than CuPy arrays (#1235, thanks @hyabe!)
Remove memory copy in the cupy.diag function (#1337)
Support weak reference to CuPy array (#1359)
Fix to preserve dtype of an input array in cupy.linalg.norm (#1376)
Improve performance of ndarray initialization (#1377)
Round-up pooled memory allocation size with clp2 (#1386)
Reduce GPU memory usage in (de)convotion (#1387)
Support 'f' and 'c' in the order option of ndarray (#1390)

Fix cupy.matmul when inputs contain zero-sized array(s) (#1238)
Fix default dtype of cupy.full (#1257)
Fix dtype option of cupy.sum and cupy.prod (#1259)
sort, lexsort, and argsort catch C++ exceptions from Thrust (#1290)
Fix view of zero-dim ndarray (#1291)
Fix real and imag of zero-dim ndarray (#1292)
Support cupy.expm1, cupy.log1p, cupy.log2 for complex type (#1293)
Fix unary functions in cupy.math.misc to support complex types (#1297)
Fix binary functions in cupy.math.misc to support complex types (#1298)
Fix OutOfMemoryError raised even when there are sufficient large freeable chunks (#1301, thanks @hyabe!)
Fix astype for complex dtypes (#1302)
Fix real, imag of non-contiguous complex ndarray (#1306)
Rounding functions support complex ndarrays (#1308)

Update README to encourage use of wheels (#1296)
Add NumPy 1.14 to supported versions (#1305)
Fix typo in sparse matrix docs (#1310)
Force displaying known methods which are mis-recognized as attributes by Sphinx (#1314)
Expand reference on differences in zero-dimensional arrays (#1315)
Split LICENSE file (#1326)
Fix typo in profiler docs (#1328)
Reorganize license files (#1335)
Fix typos in cupy.zeros and cupy.zeros_like (#1360)
Update requirements for v5.0.0b2 / v4.2 release (#1373)