2021-11-11 00:22:13 +0200 marked best answer Error computing kernel of matrix over symbolic ring I am trying to compute the kernel of the Laplacian of the hypercube graph where all nonzero entries are symbolic variables. The below code works for N=2 N = 3 #dimension of hypercube graph G = graphs.CubeGraph(N).to_directed() #Assign edge labels as symbolic variables for u,v,l in G.edges(sort=False): this_label = 'e' + str(u) + 'e' + str(v) G.set_edge_label(u, v, this_label) var(this_label) #relabel vertices to facilitate conversion to matrix G.relabel() #Create edge dictionary to facilitate conversion to matrix edge_dict = {(u,v):k for u,v,k in G.edges()} #Construct Laplacian matrix temp = matrix(SR, G.order(), G.order(), edge_dict) L = temp - diagonal_matrix(sum(temp)) #compute Laplacian kernel ker = transpose(L).kernel();  but gives the below error for N=3 at the last line: TypeError: ECL says: THROW: The catch RAT-ERR is undefined. During handling of the above exception, another exception occurred: ... TypeError: Multiplying row by Symbolic Ring element cannot be done over Symbolic Ring, use change_ring or with_added_multiple_of_row instead.  Any ideas as to the cause of the error? Can SAGE handle computing kernels of symbolic matrices of this size? Thanks! 2021-11-11 00:22:13 +0200 received badge ● Scholar (source) 2021-11-10 22:21:29 +0200 commented answer Error computing kernel of matrix over symbolic ring Wow, this is fantastic! Thank you! I am using Sage 9.3 and making your changes does indeed solve this quickly for N=3. M 2021-11-09 16:00:24 +0200 asked a question Error computing kernel of matrix over symbolic ring Error computing kernel of matrix over symbolic ring I am trying to compute the kernel of the Laplacian of the hypercube