Down below I am sharing with you the question and what I wrote as a solution so far. It includes the commands, functions, outputs, and errors. I am struggling with fixing my errors as I have tried numerous ways to correct them. However, I either get new errors or previous errors. Was wondering if someone can look at it and provide me advice, and a possible solution to the problem. 

In this question, you are given a cypher that was obtained using a Vigenere cypher, care of question 2, and are asked to decipher it.  You will use the approach outlined in Section 5.2 of the text.  There are two steps:  1)  Determine the key length by finding the shift which produces the maximum number of coincidences, 2)  use frequency analysis on the subsequences obtained by selecting symbols from the cypher at multiples of the key length to determine the key.  The details of these steps will be outlined below.  You will be asked to write several maple procedures that assist in this process.

restart;
with(StringTools):

with(LinearAlgebra):
cstr := "eqjyvxvgiuphmrrrgzhvwrrukmrtijfbtodidtsjsgofwmfalkeveolqlmhkfhrerhwuidejonvjuumklhliiwwnajxbonjthitzsqufklhihrvditvvvzhvwhihrvditvvvgsrrbunvqlmhkvhgdzpbmuvwvloiqdiiglhxtyewosksvgyklhecfrykyrqhgnzrjhukxkknwvrswyewosbrrcnfjnodumfuuchqutjysvojikomtesgbcirlcfrvzrlgwonxeqeowxkkmfvhgbjxuasvguepksjxaglvomrhhapdcponuewuntiwnakxkosnevufrwlspcivvetmhyslgknoniykrrwzuuchdvpveuzoklhirlhhonkioretxrltyivgicsugbjsoatvpbonjsoabcizotysxztyinky";
cstr := "eqjyvxvgiuphmrrrgzhvwrrukmrtijfbtodidtsjsgofwmfalkeveol\

  qlmhkfhrerhwuidejonvjuumklhliiwwnajxbonjthitzsqufklhihrvditvvv\

  zhvwhihrvditvvvgsrrbunvqlmhkvhgdzpbmuvwvloiqdiiglhxtyewosksvgy\

  klhecfrykyrqhgnzrjhukxkknwvrswyewosbrrcnfjnodumfuuchqutjysvoji\

  komtesgbcirlcfrvzrlgwonxeqeowxkkmfvhgbjxuasvguepksjxaglvomrhha\

  pdcponuewuntiwnakxkosnevufrwlspcivvetmhyslgknoniykrrwzuuchdvpv\

  euzoklhirlhhonkioretxrltyivgicsugbjsoatvpbonjsoabcizotysxztyin\

  ky"

n := Length(cstr);
                            n := 429

a)  Determine the key length.  Write a Maple function to determine the key length given the ciphertext obtained from a Vigenere cipher with unknown key using a specified alphabet.  Use one of the methods outlined in section 5.2 of the text: the Kasiski test (using trigrams) or the index of coincidence test. For the Kasiski test, the key length is suggested by the greatest common divisor of the distances between most of the repeated trigrams. For the index of coincidence test, construct the subsequences described in part (b) for various values of 
k;
. The 
k;
 value that yields the highest average index of coincidence of these subsequences most likely is the key length. 

KasiskiTest := proc(str)
  local i, j, n, trigrams, distances, gcds, freqs;
  n := StringTools:-Length(str);
  trigrams := table();
  distances := table();
  gcds := table();
  freqs := table();
  for i from 1 to n-2 do
    trigrams[str[i..i+2]] := [op(trigrams[str[i..i+2]]),i];
  end do;
  for j in trigrams do
    if nops(trigrams[j]) > 1 then
      distances[j] := map(diff,trigrams[j]);
      gcds[j] := igcd(op(distances[j]));
      freqs[gcds[j]] := freqs[gcds[j]] + 1;
    end if;
  end do;
  return maxloc(freqs);
end;

IndexCoincidenceTest := proc(str)
  local i, k, n, m, L, C, Convert, IC, avgIC;
  Convert := table();  n := StringTools:-Length(str);  
  for i from 1 to n do
    Convert[str[i]] := i-1;
  end do;
  L := Letter2Number(str,Convert); 
  IC := [];
  avgIC := [];
  for k from 1 to n/2 do
    C := [];
    for i from 1 to k do
      C[i] := seq(L[i+j*k],j=0..floor((n-i)/k));
    end do;
    IC[k] := map(DotProduct,C,C)/nops(C)^2;
    avgIC[k] := add(IC[k])/k;
  end do;
  return maxloc(avgIC);
end;

KasiskiTest(cstr);

                         maxloc(freqs)

IndexCoincidenceTest(cstr);
Error, (in IndexCoincidenceTest) expression sequences cannot be assigned to lists

b) Construct subsequences of the cypher by selecting characters at multiples of the key length.  I.E.  If k is the key length, then construct subsequences:  c1 = cstr[1],cstr[1+k],...,cstr[1+n/k],...,ck = cstr[k],cstr[2*k],...,cstr[floor(n/k)*k].  

Maple hint:  use seq and cat to form these strings.

cstr := "eqjyvxvgiuphmrrrgzhvwrrukmrtijfbtodidtsjsgofwmfalkeveolqlmhkfhrerhwuidejonvjuumklhliiwwnajxbonjthitzsqufklhihrvditvvvzhvwhihrvditvvvgsrrbunvqlmhkvhgdzpbmuvwvloiqdiiglhxtyewosksvgyklhecfrykyrqhgnzrjhukxkknwvrswyewosbrrcnfjnodumfuuchqutjysvojikomtesgbcirlcfrvzrlgwonxeqeowxkkmfvhgbjxuasvguepksjxaglvomrhhapdcponuewuntiwnakxkosnevufrwlspcivvetmhyslgknoniykrrwzuuchdvpveuzoklhirlhhonkioretxrltyivgicsugbjsoatvpbonjsoabcizotysxztyinky";
cstr := "eqjyvxvgiuphmrrrgzhvwrrukmrtijfbtodidtsjsgofwmfalkeveol\

  qlmhkfhrerhwuidejonvjuumklhliiwwnajxbonjthitzsqufklhihrvditvvv\

  zhvwhihrvditvvvgsrrbunvqlmhkvhgdzpbmuvwvloiqdiiglhxtyewosksvgy\

  klhecfrykyrqhgnzrjhukxkknwvrswyewosbrrcnfjnodumfuuchqutjysvoji\

  komtesgbcirlcfrvzrlgwonxeqeowxkkmfvhgbjxuasvguepksjxaglvomrhha\

  pdcponuewuntiwnakxkosnevufrwlspcivvetmhyslgknoniykrrwzuuchdvpv\

  euzoklhirlhhonkioretxrltyivgicsugbjsoatvpbonjsoabcizotysxztyin\

  ky"

Subsequences := proc(str,k)
  local i, n, C, S;
  n := StringTools:-Length(str);
  C := [];
  S := [];
  for i from 1 to k do
    C[i] := seq(str[i+j*k],j=0..floor((n-i)/k));
    S[i] := cat(op(C[i]));
  end do;
  return S;
end;

Warning, (in Subsequences) `j` is implicitly declared local
 Subsequences := proc (str, k) local i, n, C, S, j; n := 

    StringTools:-Length(str); C := []; S := []; for i to k do 

    C[i] := seq(str[i+j*k], j = 0 .. floor((n-i)/k)); S[i] := 

    cat(op(C[i])) end do; return S end proc

Subsequences(cstr,4);
Error, (in Subsequences) expression sequences cannot be assigned to lists

c) Calculate the character frequencies in the substrings formed from (b).  You should construct a list F=[f1/n,...,ft/n], where fi is the number of occurrences of symbol i in the string and n is the number of symbols in the string, and t is the number of symbols in the alphabet.  Don't forget that you can use evalf() to get a floating point approximation to the fractions fi/n, and you can use CountCharacterOccurrences() from the StringTools package to obtain the number of occurrences of the ith symbol. For the alphabet use a,...,z.  See question 1.

alphabet := Iota("a".."z");
            alphabet := "abcdefghijklmnopqrstuvwxyz"

CharacterFrequencies := proc(str,alphabet)
  local i, n, t, F, C;
  n := StringTools:-Length(str);
  t := StringTools:-Length(alphabet);
  F := [];
  C := StringTools:-CountCharacterOccurrences(str);
  for i from 1 to t do
    F[i] := evalf(C[alphabet[i]]/n);
  end do;
  return F;
end;

Error, attempting to assign to `StringTools:-CharacterFrequencies` which is protected
alphabet := "abcdefghijklmnopqrstuvwxyz";
S := Subsequences(cstr,4);
CharacterFrequencies(S[1],alphabet);

            alphabet := "abcdefghijklmnopqrstuvwxyz"

Error, (in Subsequences) expression sequences cannot be assigned to lists
Error, (in StringTools:-CharacterFrequencies) first argument must be a string

d) Determine the Ceasar shifts for the 5 subsequences from (b) and hence determine the key.  This is done by comparing the frequencies computed in (c) with the standard English letter probabilities given in the list FE.

You are to write a function FindShift(F1,F2) which takes as input F1 = the standard frequencies and F2 = the shifted frequencies.  The function FindShift(F1,F2) find the shift 
                              "s"

 which minimizes the error between the two lists of frequencies.  I.E.  For each possible shift 
                  "s=0,1,...,25 = nops(F1), "

compute the sum of the squares of the difference F1[i]-F2[i+s mod 26].  Find the value of 
                              "s"

 that minimizes this sum.  This will be the most likely shift.

Note that in the above sum, you will need to correct the indexing due to the fact that Maple indexes lists and arrays starting at 1 rather than 0.

Use the function FindShift to find the key used to create the cypher cstr.

FE := [0.8167000000e-1, 0.1492000000e-1, 0.2782000000e-1, 0.4253000000e-1, .1270200000, 0.2228000000e-1, 0.2015000000e-1, 0.6094000000e-1, 0.6966000000e-1, 0.1530000000e-2, 0.7720000000e-2, 0.4025000000e-1, 0.2406000000e-1, 0.6749000000e-1, 0.7507000000e-1, 0.1929000000e-1, 0.9500000000e-3, 0.5987000000e-1, 0.6327000000e-1, 0.9056000000e-1, 0.2758000000e-1, 0.9780000000e-2, 0.2360000000e-1, 0.1500000000e-2, 0.1974000000e-1, 0.7400000000e-3];
[0.08167000000, 0.01492000000, 0.02782000000, 0.04253000000, 

  0.1270200000, 0.02228000000, 0.02015000000, 0.06094000000, 

  0.06966000000, 0.001530000000, 0.007720000000, 0.04025000000, 

  0.02406000000, 0.06749000000, 0.07507000000, 0.01929000000, 

  0.0009500000000, 0.05987000000, 0.06327000000, 0.09056000000, 

  0.02758000000, 0.009780000000, 0.02360000000, 0.001500000000, 

  0.01974000000, 0.0007400000000]

FindShift := proc(F1,F2)
  local i, s, n, t, S, M;
  n := nops(F1);
  t := nops(F2);
  S := [];
  for s from 0 to n-1 do
    S[s+1] := add((F1[i]-F2[(i+s) mod t + 1])^2,i=1..n);
  end do;
  M := minloc(S);
  return M[2]-1;
end;

 FindShift := proc (F1, F2) local i, s, n, t, S, M; n := 

    nops(F1); t := nops(F2); S := []; for s from 0 to n-1 do 

    S[s+1] := add((F1[i]-F2[(`mod`(i+s, t))+1])^2, i = 1 .. n) 

    end do; M := minloc(S); return M[2]-1 end proc

with(StringTools);
alphabet := "abcdefghijklmnopqrstuvwxyz";
cstr := "eqjyvxvgiuphmrrrgzhvwrrukmrtijfbtodidtsjsgofwmfalkeveolqlmhkfhrerhwuidejonvjuumklhliiwwnajxbonjthitzsqufklhihrvditvvvzhvwhihrvditvvvgsrrbunvqlmhkvhgdzpbmuvwvloiqdiiglhxtyewosksvgyklhecfrykyrqhgnzrjhukxkknwvrswyewosbrrcnfjnodumfuuchqutjysvojikomtesgbcirlcfrvzrlgwonxeqeowxkkmfvhgbjxuasvguepksjxaglvomrhhapdcponuewuntiwnakxkosnevufrwlspcivvetmhyslgknoniykrrwzuuchdvpveuzoklhirlhhonkioretxrltyivgicsugbjsoatvpbonjsoabcizotysxztyinky";
FE := [0.8167000000e-1, 0.1492000000e-1, 0.2782000000e-1, 0.4253000000e-1, .1270200000, 0.2228000000e-1, 0.2015000000e-1, 0.6094000000e-1, 0.6966000000e-1, 0.1530000000e-2, 0.7720000000e-2, 0.4025000000e-1, 0.2406000000e-1, 0.6749000000e-1, 0.7507000000e-1, 0.1929000000e-1, 0.9500000000e-3, 0.5987000000e-1, 0.6327000000e-1, 0.9056000000e-1, 0.2758000000e-1, 0.9780000000e-2, 0.2360000000e-1, 0.1500000000e-2, 0.1974000000e-1, 0.7400000000e-3];
Subsequences := proc(str,k)
  local i, n, C, S;
  n := StringTools:-Length(str);
  C := [];
  S := [];
  for i from 1 to k do
    C[i] := seq(str[i+j*k],j=0..floor((n-i)/k));
    S[i] := cat(op(C[i]));
  end do;
  return S;
end;
CharacterFrequencies := proc(str,alphabet)
  local i, n, t, F, C;
  n := StringTools:-Length(str);
  t := StringTools:-Length(alphabet);
  F := [];
  C := StringTools:-CountCharacterOccurrences(str);
  for i from 1 to t do
    F[i] := evalf(C[alphabet[i]]/n);
  end do;
  return F;
end;
FindShift := proc(F1,F2)
  local i, s, n, t, S, M;
  n := nops(F1);
  t := nops(F2);
  S := [];
  for s from 0 to n-1 do
    S[s+1] := add((F1[i]-F2[(i+s) mod t + 1])^2,i=1..n);
  end do;
  M := minloc(S);
  return M[2]-1;
end;
S := Subsequences(cstr,4);
F := map(CharacterFrequencies,S,alphabet);
Shifts := map(FindShift,FE,F);
KeyLetters := map(Number2Letter,Shifts,alphabet);
Key := cat(op(KeyLetters));

[Anagrams, AndMap, ApproximateSearch, ApproximateSearchAll, 

  ArithmeticMean, Border, BorderArray, BorderLength, CamelCase, 

  Capitalize, CaseJoin, CaseSplit, Center, Centre, Char, 

  CharacterFrequencies, CharacterMap, Chomp, Chop, CommonPrefix, 

  CommonSuffix, Compare, CompareCI, Compress, 

  CountCharacterOccurrences, Decode, DecodeEntities, Delete, 

  DeleteSpace, DifferencePositions, Drop, EditDistance, Encode, 

  EncodeEntities, Entropy, Escape, Exchange, 

  ExpandCharacterClass, ExpandTabs, Explode, Fence, Fibonacci, 

  Fill, FirstFromLeft, FirstFromRight, FormatMessage, FormatTime, 

  FromByteArray, Generate, GenerateIdentifier, Group, 

  HammingDistance, HammingSearch, HammingSearchAll, Has, 

  HasASCII, HasAlpha, HasAlphaNumeric, HasBinaryDigit, 

  HasControlCharacter, HasDigit, HasGraphic, HasHexDigit, 

  HasIdentifier, HasIdentifier1, HasLower, HasOctalDigit, 

  HasPrintable, HasPunctuation, HasSpace, HasUpper, HasVowel, 

  Hash, Implode, Indent, IndexOfCoincidence, Insert, Iota, 

  IsASCII, IsAlpha, IsAlphaNumeric, IsAnagram, IsBalanced, 

  IsBinaryDigit, IsConjugate, IsControlCharacter, IsDerangement, 

  IsDigit, IsEodermdrome, IsGraphic, IsHexDigit, IsIdentifier, 

  IsIdentifier1, IsLower, IsMonotonic, IsOctalDigit, 

  IsPalindrome, IsPeriod, IsPermutation, IsPrefix, IsPrimitive, 

  IsPrintable, IsPunctuation, IsSorted, IsSpace, IsSubSequence, 

  IsSuffix, IsUpper, IsVowel, Join, Kasiski, LeftFold, 

  LeftRecursivePathOrder, Length, LengthSplit, Levenshtein, 

  LexOrder, LongestCommonSubSequence, LongestCommonSubString, 

  LowerCase, LyndonFactors, Map, MatchFence, MaxChar, 

  MaximalPalindromicSubstring, Metaphone, MinChar, 

  MinimumConjugate, MonotonicFactors, NGrams, NthWord, OrMap, 

  Ord, OtherCase, Overlap, PadLeft, PadRight, ParseTime, 

  PatternCanonicalForm, PatternDictionary, PatternEquivalent, 

  Period, Permute, PrefixDistance, PrimitiveRoot, Random, 

  Randomize, Readability, RegMatch, RegSplit, RegSub, RegSubs, 

  Remove, Repeat, Repeats, RevLexOrder, Reverse, RightFold, 

  RightRecursivePathOrder, Rotate, Search, SearchAll, Select, 

  SelectRemove, Sentences, Shift, ShortLexOrder, 

  ShortRevLexOrder, SimilarityCoefficient, Snarf, Sort, 

  SortPermutation, Soundex, Split, Squeeze, Stem, StringBuffer, 

  StringSplit, SubString, Subs, Substitute, SubstituteAll, 

  SuffixDistance, Support, SyllableLength, Tabulate, Take, 

  ThueMorse, ToByteArray, Trim, TrimLeft, TrimRight, Uncompress, 

  Unique, UpperCase, Visible, WildcardMatch, WordContaining, 

  WordCount, WordEnd, WordStart, Words, WrapText]

            alphabet := "abcdefghijklmnopqrstuvwxyz"

cstr := "eqjyvxvgiuphmrrrgzhvwrrukmrtijfbtodidtsjsgofwmfalkeveol\

  qlmhkfhrerhwuidejonvjuumklhliiwwnajxbonjthitzsqufklhihrvditvvv\

  zhvwhihrvditvvvgsrrbunvqlmhkvhgdzpbmuvwvloiqdiiglhxtyewosksvgy\

  klhecfrykyrqhgnzrjhukxkknwvrswyewosbrrcnfjnodumfuuchqutjysvoji\

  komtesgbcirlcfrvzrlgwonxeqeowxkkmfvhgbjxuasvguepksjxaglvomrhha\

  pdcponuewuntiwnakxkosnevufrwlspcivvetmhyslgknoniykrrwzuuchdvpv\

  euzoklhirlhhonkioretxrltyivgicsugbjsoatvpbonjsoabcizotysxztyin\

  ky"

FE := [0.08167000000, 0.01492000000, 0.02782000000, 

  0.04253000000, 0.1270200000, 0.02228000000, 0.02015000000, 

  0.06094000000, 0.06966000000, 0.001530000000, 0.007720000000, 

  0.04025000000, 0.02406000000, 0.06749000000, 0.07507000000, 

  0.01929000000, 0.0009500000000, 0.05987000000, 0.06327000000, 

  0.09056000000, 0.02758000000, 0.009780000000, 0.02360000000, 

  0.001500000000, 0.01974000000, 0.0007400000000]

Warning, (in Subsequences) `j` is implicitly declared local
 Subsequences := proc (str, k) local i, n, C, S, j; n := 

    StringTools:-Length(str); C := []; S := []; for i to k do 

    C[i] := seq(str[i+j*k], j = 0 .. floor((n-i)/k)); S[i] := 

    cat(op(C[i])) end do; return S end proc

Error, attempting to assign to `StringTools:-CharacterFrequencies` which is protected
 FindShift := proc (F1, F2) local i, s, n, t, S, M; n := 

    nops(F1); t := nops(F2); S := []; for s from 0 to n-1 do 

    S[s+1] := add((F1[i]-F2[(`mod`(i+s, t))+1])^2, i = 1 .. n) 

    end do; M := minloc(S); return M[2]-1 end proc

Error, (in Subsequences) expression sequences cannot be assigned to lists
                             F := 

Error, invalid input: FindShift uses a 2nd argument, F2, which is missing
KeyLetters := Number2Letter(Shifts, "abcdefghijklmnopqrstuvwxyz")

            Key := Shiftsabcdefghijklmnopqrstuvwxyz

e) Decipher cstr using the key found in (d) and your DecryptVigenere routine from question 2.  Note that the encrypted text will have blanks removed.

with(StringTools);
[Anagrams, AndMap, ApproximateSearch, ApproximateSearchAll, 

  ArithmeticMean, Border, BorderArray, BorderLength, CamelCase, 

  Capitalize, CaseJoin, CaseSplit, Center, Centre, Char, 

  CharacterFrequencies, CharacterMap, Chomp, Chop, CommonPrefix, 

  CommonSuffix, Compare, CompareCI, Compress, 

  CountCharacterOccurrences, Decode, DecodeEntities, Delete, 

  DeleteSpace, DifferencePositions, Drop, EditDistance, Encode, 

  EncodeEntities, Entropy, Escape, Exchange, 

  ExpandCharacterClass, ExpandTabs, Explode, Fence, Fibonacci, 

  Fill, FirstFromLeft, FirstFromRight, FormatMessage, FormatTime, 

  FromByteArray, Generate, GenerateIdentifier, Group, 

  HammingDistance, HammingSearch, HammingSearchAll, Has, 

  HasASCII, HasAlpha, HasAlphaNumeric, HasBinaryDigit, 

  HasControlCharacter, HasDigit, HasGraphic, HasHexDigit, 

  HasIdentifier, HasIdentifier1, HasLower, HasOctalDigit, 

  HasPrintable, HasPunctuation, HasSpace, HasUpper, HasVowel, 

  Hash, Implode, Indent, IndexOfCoincidence, Insert, Iota, 

  IsASCII, IsAlpha, IsAlphaNumeric, IsAnagram, IsBalanced, 

  IsBinaryDigit, IsConjugate, IsControlCharacter, IsDerangement, 

  IsDigit, IsEodermdrome, IsGraphic, IsHexDigit, IsIdentifier, 

  IsIdentifier1, IsLower, IsMonotonic, IsOctalDigit, 

  IsPalindrome, IsPeriod, IsPermutation, IsPrefix, IsPrimitive, 

  IsPrintable, IsPunctuation, IsSorted, IsSpace, IsSubSequence, 

  IsSuffix, IsUpper, IsVowel, Join, Kasiski, LeftFold, 

  LeftRecursivePathOrder, Length, LengthSplit, Levenshtein, 

  LexOrder, LongestCommonSubSequence, LongestCommonSubString, 

  LowerCase, LyndonFactors, Map, MatchFence, MaxChar, 

  MaximalPalindromicSubstring, Metaphone, MinChar, 

  MinimumConjugate, MonotonicFactors, NGrams, NthWord, OrMap, 

  Ord, OtherCase, Overlap, PadLeft, PadRight, ParseTime, 

  PatternCanonicalForm, PatternDictionary, PatternEquivalent, 

  Period, Permute, PrefixDistance, PrimitiveRoot, Random, 

  Randomize, Readability, RegMatch, RegSplit, RegSub, RegSubs, 

  Remove, Repeat, Repeats, RevLexOrder, Reverse, RightFold, 

  RightRecursivePathOrder, Rotate, Search, SearchAll, Select, 

  SelectRemove, Sentences, Shift, ShortLexOrder, 

  ShortRevLexOrder, SimilarityCoefficient, Snarf, Sort, 

  SortPermutation, Soundex, Split, Squeeze, Stem, StringBuffer, 

  StringSplit, SubString, Subs, Substitute, SubstituteAll, 

  SuffixDistance, Support, SyllableLength, Tabulate, Take, 

  ThueMorse, ToByteArray, Trim, TrimLeft, TrimRight, Uncompress, 

  Unique, UpperCase, Visible, WildcardMatch, WordContaining, 

  WordCount, WordEnd, WordStart, Words, WrapText]

alphabet := "abcdefghijklmnopqrstuvwxyz";
            alphabet := "abcdefghijklmnopqrstuvwxyz"

cstr := "eqjyvxvgiuphmrrrgzhvwrrukmrtijfbtodidtsjsgofwmfalkeveolqlmhkfhrerhwuidejonvjuumklhliiwwnajxbonjthitzsqufklhihrvditvvvzhvwhihrvditvvvgsrrbunvqlmhkvhgdzpbmuvwvloiqdiiglhxtyewosksvgyklhecfrykyrqhgnzrjhukxkknwvrswyewosbrrcnfjnodumfuuchqutjysvojikomtesgbcirlcfrvzrlgwonxeqeowxkkmfvhgbjxuasvguepksjxaglvomrhhapdcponuewuntiwnakxkosnevufrwlspcivvetmhyslgknoniykrrwzuuchdvpveuzoklhirlhhonkioretxrltyivgicsugbjsoatvpbonjsoabcizotysxztyinky";
cstr := "eqjyvxvgiuphmrrrgzhvwrrukmrtijfbtodidtsjsgofwmfalkeveol\

  qlmhkfhrerhwuidejonvjuumklhliiwwnajxbonjthitzsqufklhihrvditvvv\

  zhvwhihrvditvvvgsrrbunvqlmhkvhgdzpbmuvwvloiqdiiglhxtyewosksvgy\

  klhecfrykyrqhgnzrjhukxkknwvrswyewosbrrcnfjnodumfuuchqutjysvoji\

  komtesgbcirlcfrvzrlgwonxeqeowxkkmfvhgbjxuasvguepksjxaglvomrhha\

  pdcponuewuntiwnakxkosnevufrwlspcivvetmhyslgknoniykrrwzuuchdvpv\

  euzoklhirlhhonkioretxrltyivgicsugbjsoatvpbonjsoabcizotysxztyin\

  ky"

Key := [19, 4, 18, 19];
                     Key := [19, 4, 18, 19]

DecryptVigenere := proc(str,key,alphabet)
  local i, n, m, L, K, C, Convert, plain;
  Convert := table();  n := StringTools:-Length(alphabet);  
  for i from 1 to n do
    Convert[alphabet[i]] := i-1;
  end do;
  L := Letter2Number(str,Convert); 
  K := Letter2Number(key,Convert);
  m := nops(K);
  C := [];
  for i from 1 to nops(L) do
    C := [op(C),L[i]-K[i mod m + 1] mod n];
  end do;  
  plain := Number2Letter(C,alphabet);
  return plain;
end;
DecryptVigenere := proc (str, key, alphabet) local i, n, m, L, 

   K, C, Convert, plain; Convert := table(); n := StringTools:-L\

  ength(alphabet); for i to n do Convert[alphabet[i]] := i-1 

   end do; L := Letter2Number(str, Convert); K := Letter2Number(\

  key, Convert); m := nops(K); C := []; for i to nops(L) do C 

   := [op(C), `mod`(L[i]-K[(`mod`(i, m))+1], n)] end do; plain 

   := Number2Letter(C, alphabet); return plain end proc

DecryptVigenere(cstr,Key,alphabet);
Number2Letter([Letter2Number("eqjyvxvgiuphmrrrgzhvwrrukmrtijfbto\

  didtsjsgofwmfalkeveolqlmhkfhrerhwuidejonvjuumklhliiwwnajxbonjt\

  hitzsqufklhihrvditvvvzhvwhihrvditvvvgsrrbunvqlmhkvhgdzpbmuvwvl\

  oiqdiiglhxtyewosksvgyklhecfrykyrqhgnzrjhukxkknwvrswyewosbrrcnf\

  jnodumfuuchqutjysvojikomtesgbcirlcfrvzrlgwonxeqeowxkkmfvhgbjxu\

  asvguepksjxaglvomrhhapdcponuewuntiwnakxkosnevufrwlspcivvetmhys\

  lgknoniykrrwzuuchdvpveuzoklhirlhhonkioretxrltyivgicsugbjsoatvp\

  bonjsoabcizotysxztyinky", Convert)[1]

   + 25 Letter2Number([19, 4, 18, 19], Convert)[2], Letter2Number("eqjyvxvgiuphmrrrgzhvwrrukmrtijfbtodidtsjsgofwmfalkeveolqlmhkfhrerhwuidejonvjuumklhliiwwnajxbonjthitzsqufklhihrvditvvvzhvwhihrvditvvvgsrrbunvqlmhkvhgdzpbmuvwvloiqdiiglhxtyewosksvgyklhecfrykyrqhgnzrjhukxkknwvrswyewosbrrcnfjnodumfuuchqutjysvojikomtesgbcirlcfrvzrlgwonxeqeowxkkmfvhgbjxuasvguepksjxaglvomrhhapdcponuewuntiwnakxkosnevufrwlspcivvetmhyslgknoniykrrwzuuchdvpveuzoklhirlhhonkioretxrltyivgicsugbjsoatvpbonjsoabcizotysxztyinky", 

  Convert)[2] + 25 Letter2Number([19, 4, 18, 19], Convert)[1]], 

  "abcdefghijklmnopqrstuvwxyz")

f) Decipher the Vigenere ciphers from Computer Problems 8 and 9 from Section 2.14 of the text.

xkju:= "xkjurowmllpxwznpimbvbqjcnowxpcchhvvfvsllfvxhazityxohulxqojaxelxzxmyjaqfs\
tsrulhhucdskbxknjqidallpqslluhiaqfpbpcidsvcihwhwewthbtxrljnrsncihuvffuxvoukjlj\
swmaqfvjwjsdyljogjxdboxajultucpzmpliwmlubzxvoodybafdskxgqfadshxnxehsaruojaqfpf\
kndhsaafvulluwtaqfrupwjrszxgpfutjqiynrxnyntwmhcukjfbirzsmehhsjshyonddzzntzmpli\
lrwnmwmlvuryonthuhabwnvw";
ocwy:= "ocwyikoooniwugpmxwktzdwgtssayjzwyemdlbnqaaavsuwdvbrflauplooubfgqhgcscmgz\
latoedcsdeidpbhtmuovpiekifpimfnoamvlpqfxejsmxmpgkccaykwfzpyuavtelwhrhmwkbbvgtg\
uvtefjlodfefkvpxsgrsorvgtajbsauhzrzalkwuowhgedefnswmrciwcpaaavogpdnfpktdbalsis\
urlnpsjyeatcuceesohhdarkhwotikbroqrdfmzghgucebvgwcdqxgpbgqwlpbdaylooqdmuhbdqgm\
yweuik";
xkju := "xkjurowmllpxwznpimbvbqjcnowxpcchhvvfvsllfvxhazityxohulx\

  qojaxelxzxmyjaqfstsrulhhucdskbxknjqidallpqslluhiaqfpbpcidsvcih\

  whwewthbtxrljnrsncihuvffuxvoukjljswmaqfvjwjsdyljogjxdboxajultu\

  cpzmpliwmlubzxvoodybafdskxgqfadshxnxehsaruojaqfpfkndhsaafvullu\

  wtaqfrupwjrszxgpfutjqiynrxnyntwmhcukjfbirzsmehhsjshyonddzzntzm\

  plilrwnmwmlvuryonthuhabwnvw"

ocwy := "ocwyikoooniwugpmxwktzdwgtssayjzwyemdlbnqaaavsuwdvbrflau\

  plooubfgqhgcscmgzlatoedcsdeidpbhtmuovpiekifpimfnoamvlpqfxejsmx\

  mpgkccaykwfzpyuavtelwhrhmwkbbvgtguvtefjlodfefkvpxsgrsorvgtajbs\

  auhzrzalkwuowhgedefnswmrciwcpaaavogpdnfpktdbalsisurlnpsjyeatcu\

  ceesohhdarkhwotikbroqrdfmzghgucebvgwcdqxgpbgqwlpbdaylooqdmuhbd\

  qgmyweuik"

 

 

Q1: Why does Maple use the bar as a delimiter for certain elliptic expressions and the comma for others?

Is that in line with: Gradshteyn and Ryzhik (G&R) and in the popular "Handbook of Mathematical Functions" edited by Abramowitz and Stegun (A&S), as stated in help(JacobiAM)?      

Q2: Can I have the comma instead of the vertical bar for the Jacobian functions?

Q3: If not, how to get a bit more space between the symbols and the bar for better readability?

 

(1) (2) (3) (4)

 

Download Argument_delimiter.mw

tortoise_draft2.mw
I am trying to use the function "rt" defined below to solve the equation "eq1", but I get an error "Error, (in PDEtools:-Solve) x is in the equation, and is not solved for". I don't quite understand what prevents me from using this function freely in expressions (for example, to plot it I must use unevaluation, etc.). Could you, please, clarify why this error occurs and how to fix it?

>  (1) >  >  (2) >  (3) >  (4) >  (5) >  Warning, `s1` is implicitly declared local to procedure `rt`   Warning, `result` is implicitly declared local to procedure `rt`   (6) >  >  Error, (in rt) invalid input: eval received NULL, which is not valid for its 2nd argument, eqns   (7) >  (8) >  (9) >  (10) >  (11) >  (12) >  (13) >  Error, (in PDEtools:-Solve) x is in the equation, and is not solved for   >

Download tortoise_draft2.mw

I'm using Windows, and putting 

Typesetting:−Settings(parserwarnings=false):

into my maple.ini didn't seem to work.  The command

rsolve({u(0) = a, u(1) = b, u(n + 1) = 2*u(n) - (-e^2 + 1)*u(n - 1)}, u(n))

generated a (to me, useless) warning that "e" is sometimes used by people to represent the base of the natural logarithms, and if I meant that, then I'd have to use the palette or exp(1).  Well, as Freud once said, sometimes "e" is just a symbol, not necessarily the base of the natural logarithms.

If I issue the command *in the worksheet* it works.  But, I really *never* want to see that warning so I would like to put it in my maple.ini file.  I have some other things in that file, which *do* get executed, so...

But maybe this is a Windows thing?

My question: how do I turn those warnings off, so I never, ever see them?

The initialization file in question:

#
# Minimal maple.ini file
# RMC 2023-05-01
plots:-setoptions(font = ["Arial", 16], labelfont = ["Arial", 16],
                  axes = boxed,
                  gridlines = true,
                  colour = black ):
Typesetting:−Settings(parserwarnings=false):
print(" Initialization complete. " );

Hi,

I am working on an optimization problem, where i want to Maximize numerically a function (it is too complex to have a deriviatve) here a pseudo code:

Maximize(f(x,y,z), initialpoint = {x=1,y=1,z=1},iterationlimit = 9999);

Now i have a constraint on (x,y,z) where I want the maximum of another function be smaller than a threshold. Problem is, that the constraints function does not put it the corresponding x,y,z tupel and therefore the maximization regarding f does not come to a solution.

Maximize(f(x,y,z), {Maximize(g(x,y,z,f),{0<f<1})[1]<Thres},initialpoint = {x=1,y=1,z=1},iterationlimit = 9999);

Maybe you guys have an idea how to solve this.

Best

 

How to get same graph from maple with finite difference method for differential equations 

I m new here how to plot this i have seen related posts no where given clear idea for FDM method

plase help me to get the results Thank you

 

 

I want to construct a quadrilateral ABCD with A = 120 degrees, B = 80 degrees, C = 110degrees. I do know how to start. How do I construct one option of a quadrilateral with measure of its four angles?

I am trying to solve the Schrodinger equation:

-y''(x) = (E-V(x))*y(x),

where the potential V(x) is not known in quadratures. The potential V(x) comes from numerical solution of ODE, and is known only a discrete set of points and given by the vector [V(x_1), V_(x_2), ...], and has the following plot:

So, the question is: what is the best way to solve this problem? (apart from the obvious choice to fit the data and solve the equation with the fitted potential)

How can I produce a graph with various values for parameters? I also attached a sample of my Maple code.

restart

with(plots);
with(plottools);
with(DEtools);

eqn1 := diff(V(t), t) = pi*p - (alpha + mu)*V(t), V(0) = ic1

eqn2 := diff(S(t), t) = alpha*V(t) + (1 - p)*pi - beta*S(t)*In(t)/N - mu*S(t), S(0) = ic2

eqn3 := diff(In(t), t) = beta*S(t)*In(t)/N - (mu + delta + gamma)*In(t), In(0) = ic3

eqn4 := diff(R(t), t) = gamma*In(t) - mu*R(t), R(0) = ic4

pi := 487845;
p := 0.948;
alpha := 0.054;
beta := 0.955;
mu := 0.005;
delta := 0.03;
localgamma := 0.935;
ic1 := 484465;
ic2 := 31999760;
ic3 := 26305;
ics4 := 12470;
dsol := dsolve([eqn1, eqn2, eqn3, eqn4], numeric);

odeplot(dsol, [[t, V(t), color = plum], [t, S(t), color = blue], [t, In(t), color = cyan], [t, R(t), color = green]], t = 0 .. 1000, view = [0 .. 1000, 0 .. 300000000], thickness = 3)
 

Let's say I want to produce a graph for eqn1 with various values of parameter p: p = 0.2, p = 0.5, p = 0.7, p = 0.8. How should I produce it?

I am trying to see the closed form solution to the following equation where the know constants are phi1, a, and b:

Z := phi__1 = arctan(a*sin(alpha__1)/(a*cos(alpha__1) - b))

I am attempting to use the "solve" command as follows:

(solve(Z, alpha__1, useassumptions) assuming (0 < a and 0 < b))

 and I definitely do not understand what Maple is producing.

Thank you.

I made the upgrade to Maple 2023 today and for fun I compiled a simple procedure. I got an error in Maple 2023. So I ran the same lines of code in Maple 2022 and eveything works. Does anyone sees this problem?

>  restart: kernelopts(version); (1) >  p := proc( x :: float ) :: float; 2.3 * x end proc: >  cp:=Compiler:-Compile(p) Error, (in Compiler:-Compile) linker exited with nonzero status 1:   >  cp(1.1) (2) >

Download compile_ex.mw

Hello Maple users,

I have the following metric:

In the calculation of the different tensors, I encounter the derivative of "v" w.r.t. "t" and "v" w.r.t. "r". Can I use the compactdisplay command so that the first derivative is with a dot over "v" and a prime beside it for the second derivative for r (or other symbols, as long as it simplifies the output.

Here is my General_metric.mw:

Thank you in advance for your troubles.

Mario

How can I make a function from the results of equation (4) in the below image from the attached file? As seen in equation (6) my attempt at doing this didn't work because it didn't evaluate to a number like equation (7) did.

I saw posts on using numeric results from solve, but I don't see how to use the equation results to make a function of x.

using_solved_equations.mw

Suppose that a procedure P is declared with option threadsafe and it has a local child procedure PC (possibly anonymous). Is their any benefit, or perhaps any detriment, to also declaring PC with option threadsafe? For example, is there any benefit or detriment to the yellow option threadsafe in this code below?:

P:= proc()
option threadsafe;
local PC:= proc() option threadsafe; (* some code *) end proc;
    (* some code *)
    PC();
    (* some code *)
end proc;