Hi, I want to diffrentiate the eA1 by y. there is a lambda in the eA1, the lambda is sqrt(x^2+y^2) with some numbers. I got error named "D::ivar: (B Sqrt[x^2+y^2])/(2 c[HBar]) is not a valid variable." How can I fix it? Thanks.
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\[Lambda] = B*Sqrt[x^2 + y^2]/(2 c\[HBar])
H[\[Lambda]]
D[log[H[\[Lambda]]], \[Lambda]]
H2[x_, y_] := log[H[B*Sqrt[x^2 + y^2]/(2 c\[HBar])]/(2 c\[HBar])]
eA1[x_, y_] =
B^2*y/(4*c^2*\[Lambda][x, y]) D[H2[x, y],
B*Sqrt[x^2 + y^2]/(2 c\[HBar])]
eA1[x, y]
eB = D[eA1[x, y], y]
