Calculating eigenvectors of symbolic matrices leads to a crash.

[sagetrac-stassev]

Below is my whole sage session with a simple example leading to the crash.

$ sage

┌───────────────────────────────────────────────────┐
│ SageMath version 7.6, Release Date: 2017-03-25    │
│ Type "notebook()" for the browser-based notebook interface.        
│
│ Type "help()" for help.     
└───────────────────────────────────────────────────┘

sage: x=var('x')
sage: matrix([ [ x,x*x ],[ 1,0 ] ]).eigenvectors_right()

------------------------------------------------------------------------
/usr/lib/python2.7/site-packages/cysignals/signals.so(+0x5187)[0x7ffa55ec9187]
/usr/lib/python2.7/site-packages/cysignals/signals.so(+0x5d05)[0x7ffa55ec9d05]
/usr/lib/python2.7/site-packages/cysignals/signals.so(+0x8278)[0x7ffa55ecc278]
/usr/lib/libpthread.so.0(+0x11940)[0x7ffa5eb58940]
/usr/lib/python2.7/site-packages/numpy/core/umath.so(+0x10cfab)[0x7ff811d5afab]
/usr/lib/libpython2.7.so.1.0(+0x481c4)[0x7ffa5edad1c4]
/usr/lib/libpython2.7.so.1.0(PyNumber_Multiply+0x29)[0x7ffa5edaf859]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalFrameEx+0x1377)[0x7ffa5ee4b0a7]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalCodeEx+0x8dc)[0x7ffa5ee538dc]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalCode+0x28)[0x7ffa5ee539e8]
/usr/lib/libpython2.7.so.1.0(PyImport_ExecCodeModuleEx+0xa7)[0x7ffa5ee63fc7]
/usr/lib/libpython2.7.so.1.0(+0xff25e)[0x7ffa5ee6425e]
/usr/lib/libpython2.7.so.1.0(+0xfff81)[0x7ffa5ee64f81]
/usr/lib/libpython2.7.so.1.0(+0x1004ec)[0x7ffa5ee654ec]
/usr/lib/libpython2.7.so.1.0(PyImport_ImportModuleLevel+0x2ae)[0x7ffa5ee65d8e]
/usr/lib/libpython2.7.so.1.0(+0xe2907)[0x7ffa5ee47907]
/usr/lib/libpython2.7.so.1.0(PyObject_Call+0x52)[0x7ffa5edb1682]
/usr/lib/libpython2.7.so.1.0(PyEval_CallObjectWithKeywords+0x56)[0x7ffa5ee49716]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalFrameEx+0x2822)[0x7ffa5ee4c552]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalCodeEx+0x8dc)[0x7ffa5ee538dc]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalCode+0x28)[0x7ffa5ee539e8]
/usr/lib/libpython2.7.so.1.0(PyImport_ExecCodeModuleEx+0xa7)[0x7ffa5ee63fc7]
/usr/lib/libpython2.7.so.1.0(+0xff25e)[0x7ffa5ee6425e]
/usr/lib/libpython2.7.so.1.0(+0x100811)[0x7ffa5ee65811]
/usr/lib/libpython2.7.so.1.0(+0xfff81)[0x7ffa5ee64f81]
/usr/lib/libpython2.7.so.1.0(+0x100209)[0x7ffa5ee65209]
/usr/lib/libpython2.7.so.1.0(PyImport_ImportModuleLevel+0x1c8)[0x7ffa5ee65ca8]
/usr/lib/libpython2.7.so.1.0(+0xe2907)[0x7ffa5ee47907]
/usr/lib/libpython2.7.so.1.0(PyObject_Call+0x52)[0x7ffa5edb1682]
/usr/lib/libpython2.7.so.1.0(PyEval_CallObjectWithKeywords+0x56)[0x7ffa5ee49716]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalFrameEx+0x2822)[0x7ffa5ee4c552]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalCodeEx+0x8dc)[0x7ffa5ee538dc]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalCode+0x28)[0x7ffa5ee539e8]
/usr/lib/libpython2.7.so.1.0(PyImport_ExecCodeModuleEx+0xa7)[0x7ffa5ee63fc7]
/usr/lib/libpython2.7.so.1.0(+0xff25e)[0x7ffa5ee6425e]
/usr/lib/libpython2.7.so.1.0(+0xfff81)[0x7ffa5ee64f81]
/usr/lib/libpython2.7.so.1.0(+0x100209)[0x7ffa5ee65209]
/usr/lib/libpython2.7.so.1.0(PyImport_ImportModuleLevel+0x183)[0x7ffa5ee65c63]
/usr/lib/libpython2.7.so.1.0(+0xe2907)[0x7ffa5ee47907]
/usr/lib/libpython2.7.so.1.0(PyObject_Call+0x52)[0x7ffa5edb1682]
/usr/lib/libpython2.7.so.1.0(PyEval_CallObjectWithKeywords+0x56)[0x7ffa5ee49716]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalFrameEx+0x2822)[0x7ffa5ee4c552]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalCodeEx+0x8dc)[0x7ffa5ee538dc]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalCode+0x28)[0x7ffa5ee539e8]
/usr/lib/libpython2.7.so.1.0(PyImport_ExecCodeModuleEx+0xa7)[0x7ffa5ee63fc7]
/usr/lib/libpython2.7.so.1.0(+0xff25e)[0x7ffa5ee6425e]
/usr/lib/libpython2.7.so.1.0(+0x100811)[0x7ffa5ee65811]
/usr/lib/libpython2.7.so.1.0(+0xfff81)[0x7ffa5ee64f81]
/usr/lib/libpython2.7.so.1.0(+0x100209)[0x7ffa5ee65209]
/usr/lib/libpython2.7.so.1.0(PyImport_ImportModuleLevel+0x1c8)[0x7ffa5ee65ca8]
/usr/lib/libpython2.7.so.1.0(+0xe2907)[0x7ffa5ee47907]
/usr/lib/libpython2.7.so.1.0(PyObject_Call+0x52)[0x7ffa5edb1682]
/usr/lib/libpython2.7.so.1.0(PyEval_CallObjectWithKeywords+0x56)[0x7ffa5ee49716]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalFrameEx+0x2822)[0x7ffa5ee4c552]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalCodeEx+0x8dc)[0x7ffa5ee538dc]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalCode+0x28)[0x7ffa5ee539e8]
/usr/lib/libpython2.7.so.1.0(PyImport_ExecCodeModuleEx+0xa7)[0x7ffa5ee63fc7]
/usr/lib/libpython2.7.so.1.0(+0xff25e)[0x7ffa5ee6425e]
/usr/lib/libpython2.7.so.1.0(+0xfff81)[0x7ffa5ee64f81]
/usr/lib/libpython2.7.so.1.0(+0x1004ec)[0x7ffa5ee654ec]
/usr/lib/libpython2.7.so.1.0(PyImport_ImportModuleLevel+0x2ae)[0x7ffa5ee65d8e]
/usr/lib/libpython2.7.so.1.0(+0xe2907)[0x7ffa5ee47907]
/usr/lib/libpython2.7.so.1.0(PyObject_Call+0x52)[0x7ffa5edb1682]
/usr/lib/libpython2.7.so.1.0(PyEval_CallObjectWithKeywords+0x56)[0x7ffa5ee49716]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalFrameEx+0x2822)[0x7ffa5ee4c552]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalCodeEx+0x8dc)[0x7ffa5ee538dc]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalCode+0x28)[0x7ffa5ee539e8]
/usr/lib/libpython2.7.so.1.0(PyImport_ExecCodeModuleEx+0xa7)[0x7ffa5ee63fc7]
/usr/lib/libpython2.7.so.1.0(+0xff25e)[0x7ffa5ee6425e]
/usr/lib/libpython2.7.so.1.0(+0x100811)[0x7ffa5ee65811]
/usr/lib/libpython2.7.so.1.0(+0xfff81)[0x7ffa5ee64f81]
/usr/lib/libpython2.7.so.1.0(+0x10029f)[0x7ffa5ee6529f]
/usr/lib/libpython2.7.so.1.0(PyImport_ImportModuleLevel+0x183)[0x7ffa5ee65c63]
/usr/lib/libpython2.7.so.1.0(+0xe2907)[0x7ffa5ee47907]
/usr/lib/libpython2.7.so.1.0(PyObject_Call+0x52)[0x7ffa5edb1682]
/usr/lib/libpython2.7.so.1.0(PyObject_CallFunctionObjArgs+0xce)[0x7ffa5edb1fae]
/usr/lib/python2.7/site-packages/sage/modules/free_module_element.so(+0x10bd2)[0x7ff841981bd2]
/usr/lib/python2.7/site-packages/sage/modules/free_module_element.so(+0x17614)[0x7ff841988614]
/usr/lib/python2.7/site-packages/sage/matrix/matrix_symbolic_dense.so(+0x6f35)[0x7ff819001f35]
/usr/lib/python2.7/site-packages/sage/matrix/matrix_symbolic_dense.so(+0x70b0)[0x7ff8190020b0]
/usr/lib/python2.7/site-packages/sage/matrix/matrix_symbolic_dense.so(+0x16665)[0x7ff819011665]
/usr/lib/python2.7/site-packages/sage/matrix/matrix_symbolic_dense.so(+0x9c4d)[0x7ff819004c4d]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalFrameEx+0x8858)[0x7ffa5ee52588]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalCodeEx+0x8dc)[0x7ffa5ee538dc]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalCode+0x28)[0x7ffa5ee539e8]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalFrameEx+0x7fb1)[0x7ffa5ee51ce1]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalCodeEx+0x8dc)[0x7ffa5ee538dc]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalFrameEx+0x5fd2)[0x7ffa5ee4fd02]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalCodeEx+0x8dc)[0x7ffa5ee538dc]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalFrameEx+0x5fd2)[0x7ffa5ee4fd02]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalCodeEx+0x8dc)[0x7ffa5ee538dc]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalFrameEx+0x5fd2)[0x7ffa5ee4fd02]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalCodeEx+0x8dc)[0x7ffa5ee538dc]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalFrameEx+0x5fd2)[0x7ffa5ee4fd02]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalCodeEx+0x8dc)[0x7ffa5ee538dc]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalFrameEx+0x5fd2)[0x7ffa5ee4fd02]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalCodeEx+0x8dc)[0x7ffa5ee538dc]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalFrameEx+0x5fd2)[0x7ffa5ee4fd02]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalCodeEx+0x8dc)[0x7ffa5ee538dc]
/usr/lib/libpython2.7.so.1.0(PyEval_EvalCode+0x28)[0x7ffa5ee539e8]
/usr/lib/libpython2.7.so.1.0(+0x108efe)[0x7ffa5ee6defe]
/usr/lib/libpython2.7.so.1.0(PyRun_FileExFlags+0x81)[0x7ffa5ee6f1c1]
/usr/lib/libpython2.7.so.1.0(PyRun_SimpleFileExFlags+0xf4)[0x7ffa5ee704e4]
/usr/lib/libpython2.7.so.1.0(Py_Main+0xce0)[0x7ffa5ee82ca0]
/usr/lib/libc.so.6(__libc_start_main+0xea)[0x7ffa5e7c243a]
python2(_start+0x2a)[0x5584c1f307ea]
------------------------------------------------------------------------
Attaching gdb to process id 28119.

Failed to run gdb.
Failed to run gdb.
Install gdb for enhanced tracebacks.
------------------------------------------------------------------------
Unhandled SIGFPE: An unhandled floating point exception occurred.
This probably occurred because a *compiled* module has a bug
in it and is not properly wrapped with sig_on(), sig_off().
Python will now terminate.
------------------------------------------------------------------------

Upstream: Fixed upstream, in a later stable release.

Component: symbolics

Keywords: eigenvalues

Author: Dave Morris

Branch/Commit: f6500fb

Reviewer: Kwankyu Lee

Issue created by migration from https://trac.sagemath.org/ticket/23332

[mforets]

comment:1

Hi,
this is running on my system:

sage: matrix([ [ x,x*x ],[ 1,0 ] ]).eigenvectors_right() 

[(-1/2*x*(sqrt(5) - 1), [(1, -1/2*(sqrt(5) + 1)/x)], 1),
 (1/2*x*(sqrt(5) + 1), [(1, 1/2*(sqrt(5) - 1)/x)], 1)]

tested both in v.7.6. and in the latest v.8.0.beta12.

(that said, i have no idea what could be the issue in your session, probably someone can answer in the usual forums).

[rwst]

Description changed:

--- 
+++ 
@@ -1,26 +1,19 @@
 Below is my whole sage session with a simple example leading to the crash.
 
+```
 $ sage
 
 ┌───────────────────────────────────────────────────┐
-
-│ [SageMath](../wiki/SageMath) version 7.6, Release Date: 2017-03-25      
-             
-  │
-
+│ SageMath version 7.6, Release Date: 2017-03-25    │
 │ Type "notebook()" for the browser-based notebook interface.        
 │
-
 │ Type "help()" for help.     
-                                       │
-
 └───────────────────────────────────────────────────┘
 
- sage: x=var('x')
+sage: x=var('x')
+sage: matrix([ [ x,x*x ],[ 1,0 ] ]).eigenvectors_right()
 
- sage: matrix([ [ x,x*x ],[ 1,0 ] ]).eigenvectors_right()
-
----
+------------------------------------------------------------------------
 /usr/lib/python2.7/site-packages/cysignals/signals.so(+0x5187)[0x7ffa55ec9187]
 /usr/lib/python2.7/site-packages/cysignals/signals.so(+0x5d05)[0x7ffa55ec9d05]
 /usr/lib/python2.7/site-packages/cysignals/signals.so(+0x8278)[0x7ffa55ecc278]
@@ -127,19 +120,17 @@
 /usr/lib/libpython2.7.so.1.0(Py_Main+0xce0)[0x7ffa5ee82ca0]
 /usr/lib/libc.so.6(__libc_start_main+0xea)[0x7ffa5e7c243a]
 python2(_start+0x2a)[0x5584c1f307ea]
-
----
+------------------------------------------------------------------------
 Attaching gdb to process id 28119.
 
 Failed to run gdb.
 Failed to run gdb.
 Install gdb for enhanced tracebacks.
-
----
+------------------------------------------------------------------------
 Unhandled SIGFPE: An unhandled floating point exception occurred.
 This probably occurred because a *compiled* module has a bug
 in it and is not properly wrapped with sig_on(), sig_off().
 Python will now terminate.
+------------------------------------------------------------------------
+```
 
----
-

[rwst]

comment:2

I'm also failing the confirmation. You seem to be using a special installation of Sage because the system Python is used. What's your setup/system?

[sagetrac-stassev]

comment:4

I'm using the archlinux sagemath package, so I reported it as an archlinux bug (https://bugs.archlinux.org/task/54620). There, I was told the following:

This is caused by ecl 16.1.3. We are applying the patch from #22191 but apparently it doesn't fix all issues

[DaveWitteMorris]

Branch: public/23332

[DaveWitteMorris]

Changed keywords from none to eigenvalues

[DaveWitteMorris]

Upstream: Fixed upstream, in a later stable release.

[DaveWitteMorris]

Commit: f6500fb