View source for E(2,1)(-z^2)=cos(z)

==Theorem==
The following formula holds for $z \in \mathbb{C}$:
$$E_{2,1}\left(-z^2\right)=\cos(z),$$
where $E_{2,1}$ denotes the [[Mittag-Leffler]] function and $\cos$ denotes [[cosine]].

==Proof==

==References==
* {{PaperReference|Mittag-Leffler Functions and Their Applications|2011|H.J. Haubold|author2=A.M. Mathai|author3=R.K. Saxena|prev=E(2,1)(z)=cosh(sqrt(z))|next=findme}}: $(2.4)$ (uses notation $E_2$ instead of $E_{2,1}$)

[[Category:Theorem]]
[[Category:Unproven]]