2020-01-28 02:02:52 -0500 received badge ● Popular Question (source) 2020-01-28 02:02:13 -0500 asked a question Why does solve() produces an error? Why does solve() produces an error? TypeError: The first argument must be a symbolic expression or a list of symbolic expressions. #!/usr/bin/env python # coding: utf-8 # In[2]: var('Ex Ey Ez') # In[3]: E=vector([Ex,Ey,Ez]) # In[4]: var('Px Py Pz') # In[5]: P=vector([Px,Py,Pz]) # In[6]: var('LAx LAy LAz LBx LBy LBz') # In[7]: LA=vector([LAx,LAy,LAz]); LB=vector([LBx,LBy,LBz]) # In[8]: var('k QAx QAy') # In[9]: QA=QAx*LA+QAy*LB # In[20]: solve(E-P==k*(E-QA), [k, QAx, QAy]) # In[24]: solve((E-P).cross_product(E-QA)==0, [QAx, QAy])  2020-01-28 01:42:04 -0500 asked a question A linear algebra solve found zero solutions, weirdly Let E, P, QA be points of a 3D space, let a*QAx+b*QAy+c*QAz==d ensures that QA is in a certain plane. Let |E P| and |E QA| be the same line. Why did my attempt to find QA found zero solutions? #!/usr/bin/env python # coding: utf-8 # In[1]: var('a b c d') # In[2]: var('Ex Ey Ez') # In[3]: E=vector([Ex,Ey,Ez]) # In[4]: var('Px Py Pz') # In[5]: P=vector([Px,Py,Pz]) # In[6]: var('k QAx QAy QAz') # In[7]: QA=vector([QAx,QAy,QAz]) # In[14]: solve([E-P==k*(E-QA), a*QAx+b*QAy+c*QAz==d], [k, QAx, QAy, QAz])  2018-01-26 11:28:41 -0500 received badge ● Nice Question (source) 2018-01-15 16:22:17 -0500 received badge ● Student (source) 2018-01-15 10:59:51 -0500 asked a question Math document containing some Sage calculations I need to write a short math text draft containing some Sage calculations. (I am a Sage novice.) What software (or software combinations) you may suggest to do this? Is it possible to do with TeXmacs? If yes, does it require to install any TeXmacs addons? I tried wiki.sagemath.org/TeXmacs but it does not work (does not appear in the list of installed plugins) with my version of TeXmacs. I prefer interactive software rather than LaTeX for this task.