        /**  Circular functions - multiple angle relations  **/
 
/*K: trigonometric functions; trigonometric relations; Sin; Cos */
/*
Usage:
        S[expr,STr[2,4,n]]      or 
        S[expr,STr[2,4]]
*/
 
STr_: Ldist

STr[2,4,1] :: Sin[$x ($n _= Intp[$n])] --> (Lcl[%n]; %n:Abs[$n]; \
        (-1)^($n<0) Ex[Sin[$x] (2Cos[$x])^Evenp[%n] \
        Sum[(-1)^k Comb[%n-k-1,k] Ex[(4-4Sin[$x]^2)^((%n-2k-1-Evenp[%n])/2)],\
        {k,0,Floor[(%n-1)/2]}]])
 
STr[2,4,2] :: Cos[$x ($n_=Intp[$n])] --> (Lcl[%n]; %n:Abs[$n]; \
        2^(%n-1) Cos[$x]^%n + %n/2 Sum[(-1)^k Comb[%n-k-1,k-1]/k \
        (2Cos[$x])^(%n-2k),{k,1,Floor[%n/2]}])
 
_XTr24a[Loaded] : 1
 
 
 
 
