[Math] Is the determinant of a complex matrix the complex conjugate of the determinant of it’s complex conjugate matrix

complex numbersmatrices

Apologies for the confusing title.

Suppose we have some square matrix $A$ with complex entries and it's conjugate matrix $\bar{A}$ whose entries are the complex conjugate of those in $A$.

Is it true that the determinant of one of them is the complex conjugate of the determinant of the other? It seems simple for small matrices but I don't know if it's true in general (or is there a transpose in there somewhere?). In other words does:
$$\overline{\left(|A|\right)}={|\overline{A}|}$$

Best Answer

For $z,w \in \mathbb{C}$, we have $\overline{zw} = \overline{z} \overline{w}$ and $\overline{z+w} = \overline{z} + \overline{w}$ etc.

The determinant is obtained by performing various addition and and multiplication operations on its entries. Since complex conjugation can be done before or after these operations, your claim $\overline{\det A} = \det \overline{A}$ holds.

Regarding your last sentence, note also that transposing a matrix does not change its determinant.