2021-02-15 19:53:28 +0200 commented answer Sympy Sagemath integration bug? Not really :(. The problem are expression such as vals[0]. If I remove those than everything runs fine. I tried sympifying everything, but that didn't work either. 2021-02-10 21:51:24 +0200 received badge ● Editor (source) 2021-02-10 21:50:46 +0200 commented question Sympy Sagemath integration bug? @EmmanuelCharpentier Sorry for creating such a strong emotional reaction. The error message by sympy was "ValueError: 1 is not an integer" - unfortunately something that didn't help me at all, so I figured there was no use in including it. Here is a link to the traceback (which is really): https://we.tl/t-JECpwPI0qp 2021-02-09 23:52:55 +0200 asked a question Sympy Sagemath integration bug? The following piece of code (never mind what it does) that uses sympy runs fine: # some code... import numpy as np import sympy as sp import matplotlib.pyplot as plt phi_1_NN, phi_2_NN = sp.symbols('general_NN test', cls=sp.Function) A11,A21,b,C11,C12,d = sp.symbols('A11 A21 b C11 C12 d') U11,U21,v,W11,W12,r = sp.symbols('U11 U21 v W11 W12 r') mylambda = sp.symbols('lambda') x = sp.symbols('x') phi_1_NN =(C11*A11**3+C12*A21**3)*x**3 + (3*b*C11*A11**2+3*b*C12*A21**2)*x**2 + (3*b**2*C11*A11+3*b**2*C12*A21)*x+b**3*C11+b**3*C12+d sp.poly(phi_1_NN,x) phi_2_NN =(W11*U11**3+W12*U21**3)*x**3 + (3*v*W11*U11**2+3*v*W12*U21**2)*x**2 + (3*v**2*W11*U11+3*v**2*W12*U21)*x+v**3*W11+v**3*W12+r sp.poly(phi_2_NN,x) final_expr = mylambda *phi_1_NN+ (mylambda -1)*phi_2_NN sp.poly(final_expr,x) arr_linspace = [] for i in range(6): arr_linspace.append(np.linspace(int(-2.), int(2.), int(4.))) mesh = np.meshgrid(*arr_linspace, indexing='ij') arr_flat = [] for m in mesh: arr_flat.append(m.flatten('C')) mat_high_dim = np.stack((np.array(arr_flat)),axis = -1)  But when I run in the next cell this code, Sagemath throws a sympy error. But when I run the piece of code at home, offline, instead of the CoCalc Server, it runs fine. # UNTIL HERE EVERYTHING RUNS FINE # BUT IF I RUN THE CODE BELOW IN MY MACHINE AT HOME IT WORKS, BUT IF I RUN IT IN SAGE, A SYMPY ERROR IS RETURNED (EVEN THOUGH AT HOME IT RUNS FINE) l = sp.symbols('l') rhs_arr = [] for vals in mat_high_dim: vals = list(map(sp.sympify,vals)) rhs_arr.append(final_expr.subs({A11:1, U11:vals[0], A21:0, U21:vals[1],b:1, v:vals[2], C11:1, W11:vals[3], C12:-2, W12:vals[4],d:3,r:vals[5], mylambda:l}))  Is this some kind of bug that Sagemath has, not having integrated sympy properly? (I tried everything to get Sagemath to work, changed the software environment to different versions of Ubuntu, bought a CoCalc licence; nothing worked)