[Numpy-discussion] KeyError with float96 in linalg.py: polyfit

Jan-Matthias Braun jan_braun at gmx.net
Tue Jul 4 05:10:18 CDT 2006


Hi all,

I'm testing some computations with float96 at the moment and right now I have 
problems with polyfit raising a KeyError for the keycode 'g', which is 
floatxx with xx>64. 

I am getting a KeyError using polyfit on some float96 values. The used 
Routines seem to know nothing about this type.

My main question is: have I missed something? Shouldn't this type be used?
Below is a more detailed descripton.

Thanks in advance,
	Jan


----------------------------------------------------------------------------


In file numpy/linalg/linalg.py, the following definitions at lines 26ff seem 
to be the offending ones:
	# Helper routines
	_array_kind = {'i':0, 'l': 0, 'q': 0, 'f': 0, 'd': 0, 'F': 1, 'D': 1}
	_array_precision = {'i': 1, 'l': 1, 'q': 1, 'f': 0, 'd': 1, 'F': 0, 'D': 1}
	_array_type = [['f', 'd'], ['F', 'D']]

Here the new typecodes are missing. I tried 
	# Helper routines
	_array_kind = {'i':0, 'l': 0, 'q': 0, 'f': 0, 'd': 0, 'g': '0', 'F': 1, 
			'D':1, 'G':1}
	_array_precision = {'i': 1, 'l': 1, 'q': 1, 'f': 0, 'd': 1, 'g': 1, 
			'F': 0, 'D': 1, 'G': 1}
	_array_type = [['f', 'd', 'g'], ['F', 'D', 'G']]

which gets me a step further to a TypeError:

  File "lib/python2.3/site-packages/numpy/linalg/linalg.py", line 454, in 
lstsq
    bstar[:b.shape[0],:n_rhs] = b.copy()
TypeError: array cannot be safely cast to required type


(Question: Why only one typecode for a type which varies in bitlength on 
different platforms? On Opteron CPU's I've seen float128 with 'g'?)

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