# How to code this formula?

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Alvin Alvin on 5 Dec 2019
Commented: Walter Roberson on 5 Dec 2019 Walter Roberson on 5 Dec 2019
Can't do that
Can't do what ?? Can't use hsv2rgb() ? Can't use logical indexing to code the R' G' B' in vectorized form? Can't use a for loop with if and elseif ?
Alvin Alvin on 5 Dec 2019
can't use logical indexing to code the R' G' B' in vectorized form and Can't use a for loop with if and elseif too
Walter Roberson on 5 Dec 2019
Rp = zeros(size(H));
Gp = zeros(size(H));
Bp = zeros(size(H));
for K = 1 : numel(H)
if H(K) < 60
Rp(K) = C(K);
Gp(K) = X(K);
Bp(K) = 0;
elseif H(K) < 120
Rp(K) = X(K);
Gp(K) = C(K);
Bp(K) = 0;
elseif
and so on
end
end
What prevents you from using a for loop with if and elseif ?

Andrei Bobrov on 5 Dec 2019
function rgb = HSVtoRGB(H,S,V)
n = numel(H);
C = V.*S;
X = C .* (1 - abs(mod(H/60,2) - 1));
A = [C, X, zeros(n,1)];
i = discretize(H,0:60:360);
j = perms(1:3);
j = j([6,4,2,1,3,5],:);
r = repmat((1:n)',1,3);
rgbs = A(sub2ind([n,3],r,j(i,:)));
rgb = 255*(rgbs + V - C);
end