#C1.txt, Jan. 18, 2024 Getting started

Help:=proc(): print(`CC(P,k1), SC(P,pi), InvPi(pi) `):end:


#CC(P,k1):  Implements the Ceaser Code
#Inputs a message, given a list of characters, P (in lower case)
#and an integer k from 0 to 25, outputs the encrypted message
#For example
#CC([d,o,r,o,n],2); should output [f,q,t,q,p]
CC:=proc(P,k1) local A,T,i1:
A:=[a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z]:
for i1 from 1 to nops(A) do
 T[A[i1]]:=A[(i1+k1-1 mod 26)+1]:
od:

[seq(T[P[i1]],i1=1..nops(P))]:

end:


#SC(P,pi): Inputs a message, given a list of characters, P (in lower case)
#and a permutation pi of outputs the encrypted message
#where the letter A[i] goes to A[pi[i]]
#For example
#SC([d,o,r,o,n],[2,3,4,...., 25,1]); should output []
SC:=proc(P,pi) local A,T,i1:
A:=[a,b,c,d,e,f,g,h,i,j,k,l,m,n,o,p,q,r,s,t,u,v,w,x,y,z]:
for i1 from 1 to nops(A) do
 T[A[i1]]:=A[pi[i1]]:
od:

[seq(T[P[i1]],i1=1..nops(P))]:

end:

#InvPi(pi): The inverse of the permutation pi. For example InvPi([2,3,4,1]) is [4,1,2,3]
InvPi:=proc(pi) local i1,sig:
for i1 from 1 to nops(pi) do
 sig[pi[i1]]:=i1:
od:
[seq(sig[i1],i1=1..nops(pi))]:
end: