it may sound a stupid question,
but I'd like to know how to retrieve in a variable the field overwhich a Matrix is defined
for example, if
K=GF(7)
M=random_matrix(K,2,2)
Is there a function where i can define for example
K'= M.field() [and K' would be equal to K]
?
M.parent() provides some information of course, but we cannot use it directly
