#11248: SVD matrix decomposition may return a non-invertible "unitary" matrix
------------------------------+---------------------------------------------
Reporter: rbeezer | Owner: jason, was
Type: defect | Status: new
Priority: major | Milestone: sage-4.7
Component: linear algebra | Keywords:
Work_issues: | Upstream: N/A
Reviewer: | Author:
Merged: | Dependencies:
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Comment(by slelievre):
Replying to [comment:34 jason]:
Jason,
My setup:
{{{
$ sw_vers
ProductName: Mac OS X
ProductVersion: 10.5.8
BuildVersion: 9L31a
$ xcodebuild -version
Xcode 3.1.4
Component versions: DevToolsCore-1204.0; DevToolsSupport-1186.0
BuildVersion: 9M2809
$ gcc --version
i686-apple-darwin9-gcc-4.2.1 (GCC) 4.2.1 (Apple Inc. build 5577)
Copyright (C) 2007 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE.
$ uname -a
Darwin U 9.8.0 Darwin Kernel Version 9.8.0: Wed Jul 15 16:55:01 PDT 2009;
root:xnu-1228.15.4~1/RELEASE_I386 i386
}}}
I downloaded the example program to `test_zgesdd.c`,
saved it in `~/Desktop/test`, saved the content of
http://pastebin.com/raw.php?i=cv6ChT4V (adding a
newline at the end) to a file named `patch.patch`,
and ran
{{{
cd ~/Desktop/test/
patch < patch.patch
gcc test_zgesdd.c -o test_zgesdd -framework Accelerate
./test_zgesdd
}}}
Output:
{{{
$ patch < patch.patch
patching file test_zgesdd.c
$ gcc test_zgesdd.c -o test_zgesdd -framework Accelerate
$ ./test_zgesdd
ZGESDD Example Program Results
Original Matrix
( -5.400000000, 7.400000000) ( 6.000000000, 6.380000000) (
9.910000000, 0.160000000) ( -5.280000000, -4.160000000)
( 1.090000000, 1.550000000) ( 2.600000000, 0.070000000) (
3.980000000, -5.260000000) ( 2.030000000, 1.110000000)
( 9.880000000, 1.910000000) ( 4.920000000, 6.310000000) (
-2.110000000, 7.390000000) ( -9.810000000, -8.980000000)
Singular values
21.755192792 16.595450169 3.973275762
Left singular vectors (stored columnwise)
( 0.547427636, 0.000000000) ( 0.763021682, 0.000000000) (
-0.343687207, 0.000000000)
( -0.035076841, -0.151484384) ( 0.270976798, -0.226375144) (
0.545726276, -0.743862082)
( 0.812990162, 0.123256143) ( -0.523110953, -0.139566162) (
0.133575771, -0.113528196)
Right singular vectors (stored rowwise)
( 0.231605313, 0.206697957) ( 0.365908960, 0.386461298) (
0.242593279, 0.328338539) ( -0.561339324, -0.372335466)
( -0.579119055, 0.403296993) ( 0.109213979, 0.172424216) (
0.596738013, -0.274928122) ( 0.159988103, 0.055108351)
( 0.604200724, 0.123371344) ( -0.189887497, 0.297220678) (
0.392106353, 0.196976354) ( 0.454514329, 0.310150370)
( 0.000000000, 0.000000000) ( 0.000000000, 0.000000000) (
0.000000000, 0.000000000) ( 0.000000000, 0.000000000)
Last row entries of Right singular vectors (stored rowwise) are zero?
True True True True
$
}}}
Samuel
--
Ticket URL: <http://trac.sagemath.org/sage_trac/ticket/11248#comment:36>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
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