feynlag.operators.D_linear¶

feynlag.operators.D_linear(expr, fields)[source]¶

Distribute ∂_μ over sums and products (linearity + Leibniz rule).

expr is the argument of a PartialMu head; fields is the collection of field symbols the derivative acts on. Non-field factors are treated as constants.

Returns the expanded expression with PartialMu applied to single fields only.