cosd() giving similar value for different angles

I have the following code. Though latitude(i) and longitude(i) have different values in degree, Ut and Un are giving the same value. Please help me to find the problem in the following code. Ut and Un should be little different than each other. Thanks a lot

data = load('LatLong.txt');

distance = data(:, 1);
speed_km = data(:, 2); 
latitude = data(:, 3); 
longitude = data(:, 4); 


for i = 1:length(speed_km)    
    speed_r(i) = speed_km(i) * cosd(latitude(i)) * cosd(longitude(i));
    speed_t(i) = speed_km(i) * cosd(latitude(i)) * sind(longitude(i));
    speed_n(i) = speed_km(i) * sind(longitude(i));
end

Ur = speed_r;
Ut = speed_t;
Un = speed_n;

figure; 
plot(distance, Ur, 'b'); 
hold on 
plot(distance, Ut, 'r'); 
hold on 
plot(distance, Un, 'g'); % need correction for Ut and Un as I am getting only one line (green)

[Walter Roberson]

Please attach LatLong.txt for testing

[Paul]

What are Ut and Un?

[Ismita]

Thanks @Walter Roberson, I have attached the txt file.

Thanks @Paul. Ur, Ut and Un are speed in RTN coordinate. Ur is ok but Ut and Un should be little different. Comparing

speed_t(i) = speed_km(i) * cosd(latitude(i)) * sind(longitude(i));
speed_n(i) = speed_km(i) * sind(longitude(i)); 

I have found that cosd(latitude) is just 1 for all i as the code is taking instead of the small variation

Answer 1

[Paul]

data = load('LatLong.txt');
speed_km = data(:, 1); 
latitude = data(:, 2); 
longitude = data(:, 3); 

The latitude is quite small, assuming it's actually in degrees.

figure
plot(latitude)

However, the cosd of the latitude isn't exactly one, though it's quite close to one as expected.

figure
plot(cosd(latitude))