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Why i am getting wrong value of abcd ?

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Mahesh
Mahesh 2014-6-2
评论： Star Strider 2014-6-2
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

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回答（2 个）

Star Strider
Star Strider 2014-6-2
编辑：Star Strider 2014-6-2
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.
  2 个评论
Mahesh
Mahesh 2014-6-2
I want to measure in degree that why i have write sind.
why i am getting wrong answer in this?
Star Strider
Star Strider 2014-6-2
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

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Roger Wohlwend
Roger Wohlwend 2014-6-2
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.

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