make get_memory_usage() return a float on all platforms #4971
Description
From http://groups.google.com/group/sage-support/t/58b8f491e4906f71
If you know the limitations of get_memory_usage() you can work
around them. Case in point from 3.2.3 right after startup:
64 bit linux, i.e. sage.math:
sage: get_memory_usage()
668.32421875
----
32 bit OSX 10.5:
sage: get_memory_usage()
'131M+'
----
64 bit OSX 10.5:
sage: get_memory_usage()
'171M+'
---
32 bit Solaris/Sparc:
sage: get_memory_usage()
'81M'
While there should be a difference between 32 and 64 bit, i.e 64 bit
code is larger and consumes more memory, the result from Linux is not
even close to the truth, i.e. I don't think 32 bit Solaris is roughly
a magnitude more efficient than 64 bit Linux.
Either way, the result of get_memory_usage() should be consistent
across platforms and not return a string in some cases and something
else on Linux. It should be a float of the memory used in MB.
William then replied:
+1 Create a trac ticket. This will be an easy point for the
"fix-the-most-trac-bugs-in-sage contest we're having next week.
Component: misc
Issue created by migration from https://trac.sagemath.org/ticket/4971