# how to order a parameter by power?

for example, y=a x^2+ a(b x^2)+c^3 x^2+z^2+c z how to tansfer function y to formart like y=?x^2+ ?x+? and y=?z^2+?z+? So, I want to tansfer the equation below to arrange both A_{2l} and A_{2h} (one answer is ascending the order of A_{2l} while another answer is ascending order A_{2h})in ascending order. Thank you so much.

(-4 (Subscript[c, n] + Subscript[c, nature] - Subscript[\[Delta],
m]) + k (-2 Subscript[A, 2 l] (-1 + Subscript[c, l]) +
Subscript[A,
2 h] (2 -
Subscript[c,
h] (2 + (2 + k Subscript[A, 2 l]) Subscript[\[Lambda], h]) +
Subscript[\[Lambda],
h] (-2 + 4 Subscript[c, n] + 4 Subscript[c, nature] +
2 k Subscript[A, 2 h] (-1 + Subscript[\[Lambda], h]) +
2 Subscript[\[Delta], m] (-1 + Subscript[\[Lambda], h]) +
k Subscript[A,
2 l] (-2 + Subscript[c,
l] + (1 - Subscript[c, l] + Subscript[c, n] + Subscript[
c, nature]) Subscript[\[Lambda], h]))) +
Subscript[A,
2 l] (-2 (1 + k Subscript[A, 2 l] + Subscript[c, l] -
2 Subscript[c, n] - 2 Subscript[c, nature] +
Subscript[\[Delta], m]) +
k Subscript[A,
2 h] (-2 + Subscript[c, h] - Subscript[c,
l] + (Subscript[c, h] + Subscript[c, l] -
2 (-1 + Subscript[c, n] + Subscript[c,
nature])) Subscript[\[Lambda],
h])) Subscript[\[Lambda], l] +
Subscript[A,
2 l] (k Subscript[A,
2 h] (1 - Subscript[c, h] + Subscript[c, n] + Subscript[c,
nature]) +
2 (k Subscript[A, 2 l] + Subscript[\[Delta], m]))
\!$$\*SubsuperscriptBox[\(\[Lambda]$$, $$l$$, $$2$$]\) -
2 Subscript[A,
2] (2 + k Subscript[A,
2 h] (-1 + Subscript[\[Lambda], h]) Subscript[\[Lambda], h] +
k Subscript[A,
2 l] (-1 + Subscript[\[Lambda], l]) Subscript[\[Lambda],
l])))

• If you are typing these by hand, you can use HoldForm. For example HoldForm[y^2 + x^2]. If it is an output from a computation you will likely have to select the elements, convert them to strings, join them together etc..any reason why you want it to be so ? May 26, 2017 at 13:10
• because I want to analysis the relationship between y and A_{2l} , also the relationship between y and A_{2h} May 26, 2017 at 13:26

Use indexed variables. Subscripts cannot be variables.

Format[c[n_]] := Subscript[c, n];
Format[δ[n_]] := Subscript[δ, n];
Format[A[n_]] := Subscript[A, n];
Format[λ[n_]] := Subscript[λ, n];

expr = -4 (c[n] + c[nature] - δ[m]) +
k (-2 A[2 l] (-1 + c[l]) +
A[2 h] (2 -
c[h] (2 + (2 + k A[2 l]) λ[h]) + λ[
h] (-2 + 4 c[n] + 4 c[nature] +
2 k A[2 h] (-1 + λ[h]) +
2 δ[m] (-1 + λ[h]) +
k A[2 l] (-2 +
c[l] + (1 - c[l] + c[n] + c[nature]) λ[h]))) +
A[2 l] (-2 (1 + k A[2 l] + c[l] - 2 c[n] -
2 c[nature] + δ[m]) +
k A[2 h] (-2 + c[h] -
c[l] + (c[h] + c[l] -
2 (-1 + c[n] + c[nature])) λ[h])) λ[
l] + A[2 l] (k A[2 h] (1 - c[h] + c[n] + c[nature]) +
2 (k A[2 l] + δ[m])) λ[l]^2 -
2 A[2] (2 + k A[2 h] (-1 + λ[h]) λ[h] +
k A[2 l] (-1 + λ[l]) λ[l]));


Then use Collect

(expr21 = Collect[expr, A[2 l]])


(expr22 = Collect[expr, A[2 h]])