cdn_ehlich {HadamardR} | R Documentation |
Checks Hadamard Matrix can be constructed using Ehlich's method.
cdn_ehlich(order)
order |
integer |
Ehlich (1965)'s construction method requires order of the Hadamard matrix must be a of the form (n-1)^2. Conditions are (i)Order=(n-1)^2; (ii) n is a prime or prime power and 3(mod 4). (iii) (n-2) must be a prime or prime power. In case, if all the three conditions are satisfied, function will return 4 or NULL.
4 or NULL
Ehlich, H. (1965). Neue Hadamard-matrizen. Arch. Math., 16, 34-36.
had_ehlich
for Ehlich's construction method.
cdn_ehlich(36)
#Condition 1:(n-1)^2 = 36 = 6^2
#Condition 2: n=7 (prime)and n=3(mod 4)
#Condition 3: n-2=5 (prime)
#Return
#4
cdn_ehlich(64)
#Condition 1:(n-1)^2 = 64 = 8^2
#Condition 2: n=9 (prime power) but n=1(mod 4).
#Condition 2 fails
#Return
#NULL