jacobi_cn( z , m )
The Jacobi cn function of z and parameter m in SageMath. Defined as the cosine of the Jacobi amplitude:
\[ \operatorname{cn}( u | m ) = \cos [ \operatorname{am}( u | m ) ] \]Note that all Jacobi elliptic functions in SageMath use the parameter rather than the elliptic modulus k, which is related to the parameter by \( m = k^2 \).
Plot on the real axis:
Series expansion about the origin:
Special values:
Related functions: jacobi_am jacobi_sn jacobi_dn
Function category: Jacobi elliptic functions sagemath-docs