I was attempting to replicate the examples seen here (http://www.sagemath.org/doc/reference/interfaces/sage/interfaces/qepcad.html), but I keep getting errors.
Given ︠482004e5-daf3-4312-b5d7-a61b41d210a4s︠ var('a,b,c,d,x,y,z') qf = qepcad_formula;
ellipse = 3x^2 + 2x*y + y^2 - x + y - 7 F = qf.exists(y, ellipse == 0); F qepcad(F)
︡202e02ca-ac90-4b34-afab-7d6ceb6d41f5︡{"stdout":"(a, b, c, d, x, y, z)\n"}︡{"stdout":"(E y)[3 x^2 + 2 x y + y^2 - x + y - 7 = 0]\n"}︡{"stderr":"Error in lines 5-5\n"}︡{"stderr":"Traceback (most recent call last):\n File \"/projects/45572f4b-6bd1-49bd-9d46-5f340788b465/.sagemathcloud/sage_server.py\", line 879, in execute\n exec compile(block+'\n', '', 'single') in namespace, locals\n File \"\", line 1, in <module>\n File \"/usr/local/sage/sage-6.5/local/lib/python2.7/site-packages/sage/interfaces/qepcad.py\", line 1431, in qepcad\n qe = Qepcad(formula, vars=vars, **kwargs)\n File \"/usr/local/sage/sage-6.5/local/lib/python2.7/site-packages/sage/interfaces/qepcad.py\", line 777, in __init__\n qex._send('[ input from Sage ]')\n File \"/usr/local/sage/sage-6.5/local/lib/python2.7/site-packages/sage/interfaces/expect.py\", line 212, in _send\n self._start()\n File \"/usr/local/sage/sage-6.5/local/lib/python2.7/site-packages/sage/interfaces/expect.py\", line 445, in _start\n raise RuntimeError(\"unable to start %s\" % self.name())\nRuntimeError: unable to start QEPCAD\n"}︡ ︠5c912bc8-cd8b-495c-9fa3-eda33c34530e︠
