I was trying to define a function of form f_{i_1,i_2,i_3,i_4}(x,y,z) using the command
function('f_{i_1,i_2,i_3,i_4}',x,y,z)
but sage gave me back the error that 'tuple' object is not callable. I can define it like
function('f_{i_1}_{i_2}_{i_3}_{i_4}',x,y,z)
but it is not a good way when the indices are many or maybe even I should use
function('f_i_1_i_2_i_3_i_4',x,y,z)
instead?
