Elementwise versus matrix functions

Both elementwise and matrix functions are very useful in practice. In Matlab there are two versions of operators: the plain operators (matrix operation like *) and dot operators (elementwise operations like .*), and two versions of functions: the plain functions (elementwise like exp) and m-suffixed functions (matrix functions like expm).

Two difficulties exist,

• Python do not recognize these ``dot operators''. This may be overcome by patching the parser like what has been done for the ``augmentation operators'' += and *=, etc. Discussions and experiments are underway. Right now A .* B can be invoked by A.__dotmul__(B).
• The default behavior in Matlab is for the symbolic operators like *, / is different from that for the named functions like exp, sin. This leaves the function pow potentially confusing. Is pow(x,2)==x.**2 or pow(x,2)==x**2? The safest approach appears to be leaving out this function.