[math-fun] limited development of some special functions

I noticed an error in my last post correction of derivations diff(qanh(x),x)=1/(qosh(x))^2;diff(cqnh(x),x)=-1/(qinh(x))^2; limited development of functions to order 16; I found qosh(x)=1+(1/4)*x^4+(9/160)*x^8+(149/9600)*x^(12)+(15147/3328000)*x^16; qinh(x)=x+(3/20)*x^5+(19/480)*x^9+(469/41600)*x^13+(189611/56576000)*x^17; I deduce without verifying that: qos(x)=1-(1/4)*x^4+(9/160)*x^8-(149/9600)*x^(12)+(15147/3328000)*x^16; qin(x)=x-(3/20)*x^5+(19/480)*x^9-(469/41600)*x^13+(189611/56576000)*x^17;