Why i am getting wrong value of abcd ?

I am trying to solve this code. In code inc(1,3)=139 and it give abcd(1,3) for 139 equal to 0.65 whereas when i solve it manually sin(139)=0.81. why i am getting wrong value ? and when i find value of abcd(1,4)=0.8 nearer to 0.81 which should be at abcd(1,3). Please help me solving in this

clear all

clc

Dec=[-23.01, -23.01, -23.01, -23.01, -23.01, -23.01, -23.01, -23.01, -23.01, -23.01];

Omega=[-165, -150, -135, -120, -105, -90, -75, -60, -45, -30];

phi=33.7;

for t=1:10;

phi=33.6;

angle1(1,t)=cosd(phi)*cosd(Dec(1,t))*cosd(Omega(1,t));

angle2(1,t)=sind(phi)*sind(Dec(1,t));

inc(1,t)=acosd(angle1(1,t)+angle2(1,t));

% re(1,t)=asind(sind(inc(1,t))/1.33); % Reflection angle is found by assumed incident angle

    abcd(1,t)=sind(inc(1,t));

end

Answer 1

[Star Strider]

If you want the sin() with a radian argument, change your statement to:

abcd(1,t)=sin(inc(1,t));

However all of your angle calculations otherwise are in degrees, not radians, so this will likely not give you the correct answer.

[Mahesh]

I want to measure in degree that why i have write sind.

why i am getting wrong answer in this?

[Star Strider]

You are using ‘grad’ angle units in your hand calculator calculations, not degrees:

sin(139 degs) = 0.65605902899050728478249596402342
sin(139 grad) = 0.81814971742502343212965828088413

(These from Windows Calculator.)

In MATLAB:

abcd_deg = sind(139)
abcd_rad = sin(139)
abcd_grd = sin(139*(pi/200))

produces:

abcd_deg =

     656.0590e-003

abcd_rad =

     696.0801e-003

abcd_grd =

     818.1497e-003

Answer 2

[Roger Wohlwend]

You don't get the wrong values. sin(139) = 0.81, that is right, but that is not what your code calculates. It calculates sind(139) and that is 0.65.

[Mahesh]

Yes i know, thats why i am asking how to correct this ?