QEPCAD giving an error

[anirjoshi]

Steps To Reproduce

I have installed sage using the following command:
sudo apt-get install sagemath

Then in running sage, I get the command prompt of sage.
Then I try to run the following commands as mentioned in the tutorial here

var('a,b,c,d,x,y,z')
qf = qepcad_formula
ellipse = 3*x^2 + 2*x*y + y^2 - x + y - 7
F = qf.exists(y, ellipse == 0);
qepcad(F)

On running qepcad(F), I get the following error:

---------------------------------------------------------------------------
OSError                                   Traceback (most recent call last)
/usr/lib/python3/dist-packages/pexpect/spawnbase.py in read_nonblocking(self, size, timeout)
    165         try:
--> 166             s = os.read(self.child_fd, size)
    167         except OSError as err:

OSError: [Errno 5] Input/output error

During handling of the above exception, another exception occurred:

EOF                                       Traceback (most recent call last)
/usr/lib/python3/dist-packages/pexpect/expect.py in expect_loop(self, timeout)
    110                 # Still have time left, so read more data
--> 111                 incoming = spawn.read_nonblocking(spawn.maxread, timeout)
    112                 if self.spawn.delayafterread is not None:

/usr/lib/python3/dist-packages/pexpect/pty_spawn.py in read_nonblocking(self, size, timeout)
    484         if self.child_fd in r:
--> 485             return super(spawn, self).read_nonblocking(size)
    486 

/usr/lib/python3/dist-packages/pexpect/spawnbase.py in read_nonblocking(self, size, timeout)
    170                 self.flag_eof = True
--> 171                 raise EOF('End Of File (EOF). Exception style platform.')
    172             raise

EOF: End Of File (EOF). Exception style platform.

During handling of the above exception, another exception occurred:

EOF                                       Traceback (most recent call last)
/usr/lib/python3/dist-packages/sage/interfaces/expect.py in _start(self, alt_message, block_during_init)
    518         try:
--> 519             self._expect.expect(self._prompt)
    520         except (pexpect.TIMEOUT, pexpect.EOF) as msg:

/usr/lib/python3/dist-packages/pexpect/spawnbase.py in expect(self, pattern, timeout, searchwindowsize, async_, **kw)
    339         compiled_pattern_list = self.compile_pattern_list(pattern)
--> 340         return self.expect_list(compiled_pattern_list,
    341                 timeout, searchwindowsize, async_)

/usr/lib/python3/dist-packages/pexpect/spawnbase.py in expect_list(self, pattern_list, timeout, searchwindowsize, async_, **kw)
    368         else:
--> 369             return exp.expect_loop(timeout)
    370 

/usr/lib/python3/dist-packages/pexpect/expect.py in expect_loop(self, timeout)
    116         except EOF as e:
--> 117             return self.eof(e)
    118         except TIMEOUT as e:

/usr/lib/python3/dist-packages/pexpect/expect.py in eof(self, err)
     62                 msg = str(err) + '\n' + msg
---> 63             raise EOF(msg)
     64 

EOF: End Of File (EOF). Exception style platform.
Qepcad finished running /usr/bin/env qe=/usr qepcad
command: /usr/bin/env
args: ['/usr/bin/env', 'qe=/usr', 'qepcad']
buffer (last 100 chars): b''
before (last 100 chars): b'/usr/bin/env: \xe2\x80\x98qepcad\xe2\x80\x99: No such file or directory\r\n'
after: <class 'pexpect.exceptions.EOF'>
match: None
match_index: None
exitstatus: 127
flag_eof: True
pid: 8838
child_fd: 20
closed: False
timeout: None
delimiter: <class 'pexpect.exceptions.EOF'>
logfile: None
logfile_read: None
logfile_send: None
maxread: 4194304
ignorecase: False
searchwindowsize: None
delaybeforesend: None
delayafterclose: 0.1
delayafterterminate: 0.1
searcher: searcher_re:
    0: re.compile(b'\nEnter an .*:\r')

During handling of the above exception, another exception occurred:

RuntimeError                              Traceback (most recent call last)
<ipython-input-6-63f2a929c2ee> in <module>
----> 1 qepcad(F)

/usr/lib/python3/dist-packages/sage/interfaces/qepcad.py in qepcad(formula, assume, interact, solution, vars, **kwargs)
   1627             use_witness = True
   1628 
-> 1629     qe = Qepcad(formula, vars=vars, **kwargs)
   1630     if assume is not None:
   1631         qe.assume(assume)

/usr/lib/python3/dist-packages/sage/interfaces/qepcad.py in __init__(self, formula, vars, logfile, verbose, memcells, server)
    874 
    875         qex = Qepcad_expect(logfile=logfile, memcells=memcells, server=server)
--> 876         qex._send('[ input from Sage ]')
    877         qex._send('(' + ','.join(varlist) + ')')
    878         qex._send(str(free_vars))

/usr/lib/python3/dist-packages/sage/interfaces/expect.py in _send(self, cmd)
    271     def _send(self, cmd):
    272         if self._expect is None:
--> 273             self._start()
    274         E = self._expect
    275         self.__so_far = ''

/usr/lib/python3/dist-packages/sage/interfaces/expect.py in _start(self, alt_message, block_during_init)
    521             self._expect = None
    522             self._session_number = BAD_SESSION
--> 523             raise RuntimeError("unable to start %s: %s" % (self.name(), msg))
    524         self._expect.timeout = None
    525 

RuntimeError: unable to start QEPCAD: End Of File (EOF). Exception style platform.
Qepcad finished running /usr/bin/env qe=/usr qepcad
command: /usr/bin/env
args: ['/usr/bin/env', 'qe=/usr', 'qepcad']
buffer (last 100 chars): b''
before (last 100 chars): b'/usr/bin/env: \xe2\x80\x98qepcad\xe2\x80\x99: No such file or directory\r\n'
after: <class 'pexpect.exceptions.EOF'>
match: None
match_index: None
exitstatus: 127
flag_eof: True
pid: 8838
child_fd: 20
closed: False
timeout: None
delimiter: <class 'pexpect.exceptions.EOF'>
logfile: None
logfile_read: None
logfile_send: None
maxread: 4194304
ignorecase: False
searchwindowsize: None
delaybeforesend: None
delayafterclose: 0.1
delayafterterminate: 0.1
searcher: searcher_re:
    0: re.compile(b'\nEnter an .*:\r')

Expected Behavior

8 x^2 - 8 x - 29 <= 0

Actual Behavior

Error as mentioned above.

Additional Information

No response

Environment

- **OS**: I am using it on mac M2 with a docker of ubuntu 20.04
- **Sage Version**: SageMath version 9.0, Release Date: 2020-01-01

Checklist

• I have searched the existing issues for a bug report that matches the one I want to file, without success.
• I have read the documentation and troubleshoot guide

[dimpase]

SageMath version 9.0, Release Date: 2020-01-01 - sorry, we don't have resources to support such an old version.
We're now on 10.2, and have approximately 2 releases per year.

also, QEPCAD had its latest release in 2012, it'd be a miracle if it still reliably works on modern systems.

[dimpase]

I tested this example on the latest beta, 10.3.beta0, and it works and returns 8 x^2 - 8 x - 29 <= 0.

I suggest that you build Sage (latest released version, 10.2) from source, following the instructions.
First of all, uninstall apt-get installed Sage 9.0. Then,

After you dowloaded/installed the source, either using git, or untarring the tarball, run

./configure --enable-qepcad
make 

(after running ./configure have a look at its output, roughly the last page, where it suggests to install more system packages; do the suggested installations, then re-run ./configure as above, or as told )

[anirjoshi]

Running ./configure gives an error on sage 10.2:
bash: ./configure: No such file or directory

The output of ls is as follows:

AUTHORS.md          CONTRIBUTING.md  README.md        build         docker              sage
CITATION.cff        COPYING.txt      VERSION.txt      condarc.yml   m4                  src
CITATION.cff.in     Makefile         bootstrap        config        pkgs                tox.ini
CODE_OF_CONDUCT.md  Pipfile.m4       bootstrap-conda  configure.ac  pyrightconfig.json

[dimpase]

@anirjoshi - in this case first you need to run ./bootstrap