have table like table(symmetric, [() = x]) from other code not mine, strange syntax

how to extract x from table thanks

hi

i have expression like

z:=f0(x) + f1(x)*diff(y(x),x) + f2(x)*diff(y(x),x,x) + f4(x)*diff(y(x),x,x,x,x) ... etc ;

always linear terms diff((y(x),x) etc, never like diff((y(x),x)^2

want vector with coeffs of diff((y(x),x) etc in order low to high so want

<f1(x), f2(x), 0, f4(x) ...>

if z:=f0(x) + f2(x)*diff(y(x),x,x) + f4(x)*diff(y(x),x,x,x,x) ... etc ; want <0, f2(x), 0, f4(x) ...>

first term in vector always for diff((y(x),x)

how to do thanks

i have matrix M depend on x1 x2 x3 .... want limit of M. for sure can use loop like M[i,j]:=limit(M[i,j],[x1=0,x2=0,...]; i=1.. j=1..

want use map2 to do all at same time, try map2(limit,[x1=0,x2=0],M); gives error

Error, invalid input: limit expects its 1st argument, expr, to be of type Or(equation, algebraic), but received [x1 = 0, x2 = 0]

is possible to do using map or other thing not loop