http://www.neuron.yale.edu/neuron/stati ... ml#fmatrix One should call fcurrent() prior to fmatrix() to ensure the matrix is setup. The matrix printed is for thread 0. The 4 numbers printed on each line are compartment index jacobian element for parent in node equation (ClassicalNODEB) jacobian element for node in parent equation (ClassicalNODEA) diagonal element (NODED) right hand side (NODERHS)