Axis 1 is allong first dimension of detector (when not tilted), this is the slow dimension of the image array in C or Y
In[5]:= x1={1,0,0}
Out[5]= {1,0,0}
 Axis 2 is allong second dimension of detector (when not tilted), this is the fast dimension of the image in C or X
In[6]:= x2={0,1,0}
Out[6]= {0,1,0}
Axis 3 is along the incident X-Ray beam
In[7]:= x3={0,0,1}
Out[7]= {0,0,1}
In[9]:= id3={x1,x2,x3}
Out[9]= {{1,0,0},{0,1,0},{0,0,1}}
In[10]:= {{1,0,0},{0,1,0},{0,0,1}}
Out[10]= {{1,0,0},{0,1,0},{0,0,1}}
In[11]:= rotM1=RotationMatrix[rot1,x1]
Out[11]= {{1,0,0},{0,Cos[rot1],-Sin[rot1]},{0,Sin[rot1],Cos[rot1]}}
In[12]:= rotM2 =  RotationMatrix[rot2,x2]
Out[12]= {{Cos[rot2],0,Sin[rot2]},{0,1,0},{-Sin[rot2],0,Cos[rot2]}}
In[13]:= rotM3 =  RotationMatrix[rot3,x3]
Out[13]= {{Cos[rot3],-Sin[rot3],0},{Sin[rot3],Cos[rot3],0},{0,0,1}}
Rotations of the detector are applied first Rot around axis 1, then axis 2 and finally around axis 3
In[14]:= R=rotM3.rotM2.rotM1
Out[14]= {{Cos[rot2] Cos[rot3],Cos[rot3] Sin[rot1] Sin[rot2]-Cos[rot1] Sin[rot3],Cos[rot1] Cos[rot3] Sin[rot2]+Sin[rot1] Sin[rot3]},{Cos[rot2] Sin[rot3],Cos[rot1] Cos[rot3]+Sin[rot1] Sin[rot2] Sin[rot3],-Cos[rot3] Sin[rot1]+Cos[rot1] Sin[rot2] Sin[rot3]},{-Sin[rot2],Cos[rot2] Sin[rot1],Cos[rot1] Cos[rot2]}}
In[15]:= CForm[R.x1]

Out[15]//CForm=
List(Cos(rot2)*Cos(rot3),Cos(rot2)*Sin(rot3),-Sin(rot2))
In[16]:= CForm[R.x2]

Out[16]//CForm=
List(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3),Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3),Cos(rot2)*Sin(rot1))
In[17]:= CForm[R.x3]
Out[17]//CForm=
List(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3),-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3),Cos(rot1)*Cos(rot2))
In[18]:= CForm[Det[R]]
Out[18]//CForm=
Power(Cos(rot1),2)*Power(Cos(rot2),2)*Power(Cos(rot3),2) + Power(Cos(rot2),2)*Power(Cos(rot3),2)*Power(Sin(rot1),2) + Power(Cos(rot1),2)*Power(Cos(rot3),2)*Power(Sin(rot2),2) + 
   Power(Cos(rot3),2)*Power(Sin(rot1),2)*Power(Sin(rot2),2) + Power(Cos(rot1),2)*Power(Cos(rot2),2)*Power(Sin(rot3),2) + Power(Cos(rot2),2)*Power(Sin(rot1),2)*Power(Sin(rot3),2) + 
   Power(Cos(rot1),2)*Power(Sin(rot2),2)*Power(Sin(rot3),2) + Power(Sin(rot1),2)*Power(Sin(rot2),2)*Power(Sin(rot3),2)
In[13]:=
Any pixel on detector plan at coordianate (d1, d2) in meters. Detector is at z=L

In[22]:= P={d1,d2,L}
CForm[R.P]

Out[22]= {d1,d2,L}
Out[23]//CForm=
List(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),
   d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),L*Cos(rot1)*Cos(rot2) + d2*Cos(rot2)*Sin(rot1) - d1*Sin(rot2))
In[24]:= t1 = R.P.x1
CForm[t1]
Out[24]= d1 Cos[rot2] Cos[rot3]+d2 (Cos[rot3] Sin[rot1] Sin[rot2]-Cos[rot1] Sin[rot3])+L (Cos[rot1] Cos[rot3] Sin[rot2]+Sin[rot1] Sin[rot3])
Out[25]//CForm=
d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3))
In[26]:= t2 = R.P.x2
CForm[t2]
Out[26]= d1 Cos[rot2] Sin[rot3]+L (-Cos[rot3] Sin[rot1]+Cos[rot1] Sin[rot2] Sin[rot3])+d2 (Cos[rot1] Cos[rot3]+Sin[rot1] Sin[rot2] Sin[rot3])
Out[27]//CForm=
d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3))
In[28]:= t3=R.P.x3
CForm[t3]
Out[28]= L Cos[rot1] Cos[rot2]+d2 Cos[rot2] Sin[rot1]-d1 Sin[rot2]
Out[29]//CForm=
L*Cos(rot1)*Cos(rot2) + d2*Cos(rot2)*Sin(rot1) - d1*Sin(rot2)
Distance sample to detector point (d1,d2)		▼
(no Mathematica translations)  
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In[30]:= dist = Norm[R.P]
CForm[dist]
Out[30]= √(Abs[L Cos[rot1] Cos[rot2]+d2 Cos[rot2] Sin[rot1]-d1 Sin[rot2]]^2+Abs[d1 Cos[rot2] Cos[rot3]+d2 (Cos[rot3] Sin[rot1] Sin[rot2]-Cos[rot1] Sin[rot3])+L (Cos[rot1] Cos[rot3] Sin[rot2]+Sin[rot1] Sin[rot3])]^2+Abs[d1 Cos[rot2] Sin[rot3]+L (-Cos[rot3] Sin[rot1]+Cos[rot1] Sin[rot2] Sin[rot3])+d2 (Cos[rot1] Cos[rot3]+Sin[rot1] Sin[rot2] Sin[rot3])]^2)
Out[31]//CForm=
Sqrt(Power(Abs(L*Cos(rot1)*Cos(rot2) + d2*Cos(rot2)*Sin(rot1) - d1*Sin(rot2)),2) + Power(Abs(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + 
       L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3))),2) + Power(Abs(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3))),
     2))
cos(2theta) can be defined as (R.P component along x3) over the distance |R.P|
In[32]:= tthc = ArcCos [-(R.P).x3/Norm[R.P]]
CForm[tthc]

Out[32]= ArcCos[(-L Cos[rot1] Cos[rot2]-d2 Cos[rot2] Sin[rot1]+d1 Sin[rot2])/(√(Abs[L Cos[rot1] Cos[rot2]+d2 Cos[rot2] Sin[rot1]-d1 Sin[rot2]]^2+Abs[d1 Cos[rot2] Cos[rot3]+d2 (Cos[rot3] Sin[rot1] Sin[rot2]-Cos[rot1] Sin[rot3])+L (Cos[rot1] Cos[rot3] Sin[rot2]+Sin[rot1] Sin[rot3])]^2+Abs[d1 Cos[rot2] Sin[rot3]+L (-Cos[rot3] Sin[rot1]+Cos[rot1] Sin[rot2] Sin[rot3])+d2 (Cos[rot1] Cos[rot3]+Sin[rot1] Sin[rot2] Sin[rot3])]^2))]
Out[33]//CForm=
ArcCos((-(L*Cos(rot1)*Cos(rot2)) - d2*Cos(rot2)*Sin(rot1) + d1*Sin(rot2))/
    Sqrt(Power(Abs(L*Cos(rot1)*Cos(rot2) + d2*Cos(rot2)*Sin(rot1) - d1*Sin(rot2)),2) + Power(Abs(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + 
         L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3))),2) + Power(Abs(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + 
         d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3))),2)))



In[41]:= ttht = ArcTan[t3,Sqrt[t1^2 + t2^2]]

CForm[ttht]


Out[41]= ArcTan[L Cos[rot1] Cos[rot2]+d2 Cos[rot2] Sin[rot1]-d1 Sin[rot2],√((d1 Cos[rot2] Cos[rot3]+d2 (Cos[rot3] Sin[rot1] Sin[rot2]-Cos[rot1] Sin[rot3])+L (Cos[rot1] Cos[rot3] Sin[rot2]+Sin[rot1] Sin[rot3]))^2+(d1 Cos[rot2] Sin[rot3]+L (-Cos[rot3] Sin[rot1]+Cos[rot1] Sin[rot2] Sin[rot3])+d2 (Cos[rot1] Cos[rot3]+Sin[rot1] Sin[rot2] Sin[rot3]))^2)]
Out[42]//CForm=
ArcTan(L*Cos(rot1)*Cos(rot2) + d2*Cos(rot2)*Sin(rot1) - d1*Sin(rot2),Sqrt(Power(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),
      2) + Power(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),2)))
Tangeant of angle chi is defined as (R.P component along x1) over (R.P component along x2). Arctan2 should be used in actual calculation
In[36]:= chi =ArcTan[t1  , t2]
CForm[chi]
Out[36]= ArcTan[d1 Cos[rot2] Cos[rot3]+d2 (Cos[rot3] Sin[rot1] Sin[rot2]-Cos[rot1] Sin[rot3])+L (Cos[rot1] Cos[rot3] Sin[rot2]+Sin[rot1] Sin[rot3]),d1 Cos[rot2] Sin[rot3]+L (-Cos[rot3] Sin[rot1]+Cos[rot1] Sin[rot2] Sin[rot3])+d2 (Cos[rot1] Cos[rot3]+Sin[rot1] Sin[rot2] Sin[rot3])]
Out[37]//CForm=
ArcTan(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),
   d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)))
Coodinates of the Point of Normal Incidence

In[38]:= PONI = R.{0,0,L}
CForm[PONI]
Out[38]= {L (Cos[rot1] Cos[rot3] Sin[rot2]+Sin[rot1] Sin[rot3]),L (-Cos[rot3] Sin[rot1]+Cos[rot1] Sin[rot2] Sin[rot3]),L Cos[rot1] Cos[rot2]}
Out[39]//CForm=
List(L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)),L*Cos(rot1)*Cos(rot2))
Derivatives of 2Theta
In[43]:= CForm[D[ttht,d1]]
Out[43]//CForm=
((L*Cos(rot1)*Cos(rot2) + d2*Cos(rot2)*Sin(rot1) - d1*Sin(rot2))*(2*Cos(rot2)*Cos(rot3)*(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + 
           L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3))) + 2*Cos(rot2)*Sin(rot3)*
         (d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)))))/
    (2.*Sqrt(Power(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),2) + 
        Power(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),2))*
      (Power(L*Cos(rot1)*Cos(rot2) + d2*Cos(rot2)*Sin(rot1) - d1*Sin(rot2),2) + Power(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + 
          L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),2) + Power(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),2)))
     + (Sin(rot2)*Sqrt(Power(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),2) + 
        Power(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),2)))/
    (Power(L*Cos(rot1)*Cos(rot2) + d2*Cos(rot2)*Sin(rot1) - d1*Sin(rot2),2) + Power(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),
       2) + Power(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),2))
In[44]:= CForm[D[ttht,d2]]

Out[44]//CForm=
((L*Cos(rot1)*Cos(rot2) + d2*Cos(rot2)*Sin(rot1) - d1*Sin(rot2))*(2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3))*
         (d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3))) + 
        2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3))*(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)))))/
    (2.*Sqrt(Power(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),2) + 
        Power(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),2))*
      (Power(L*Cos(rot1)*Cos(rot2) + d2*Cos(rot2)*Sin(rot1) - d1*Sin(rot2),2) + Power(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + 
          L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),2) + Power(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),2)))
     - (Cos(rot2)*Sin(rot1)*Sqrt(Power(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),2) + 
        Power(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),2)))/
    (Power(L*Cos(rot1)*Cos(rot2) + d2*Cos(rot2)*Sin(rot1) - d1*Sin(rot2),2) + Power(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),
       2) + Power(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),2))
In[47]:= CForm[D[ttht,L]]
Out[47]//CForm=
((L*Cos(rot1)*Cos(rot2) + d2*Cos(rot2)*Sin(rot1) - d1*Sin(rot2))*(2*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3))*
         (d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3))) + 
        2*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3))*(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)))))/
    (2.*Sqrt(Power(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),2) + 
        Power(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),2))*
      (Power(L*Cos(rot1)*Cos(rot2) + d2*Cos(rot2)*Sin(rot1) - d1*Sin(rot2),2) + Power(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + 
          L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),2) + Power(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),2)))
     - (Cos(rot1)*Cos(rot2)*Sqrt(Power(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),2) + 
        Power(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),2)))/
    (Power(L*Cos(rot1)*Cos(rot2) + d2*Cos(rot2)*Sin(rot1) - d1*Sin(rot2),2) + Power(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),
       2) + Power(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),2))
In[48]:= CForm[D[ttht,rot1]]
Out[48]//CForm=
((L*Cos(rot1)*Cos(rot2) + d2*Cos(rot2)*Sin(rot1) - d1*Sin(rot2))*(2*(L*(-(Cos(rot3)*Sin(rot1)*Sin(rot2)) + Cos(rot1)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)))*
         (d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3))) + 
        2*(d2*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + L*(-(Cos(rot1)*Cos(rot3)) - Sin(rot1)*Sin(rot2)*Sin(rot3)))*
         (d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)))))/
    (2.*Sqrt(Power(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),2) + 
        Power(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),2))*
      (Power(L*Cos(rot1)*Cos(rot2) + d2*Cos(rot2)*Sin(rot1) - d1*Sin(rot2),2) + Power(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + 
          L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),2) + Power(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),2)))
     - ((d2*Cos(rot1)*Cos(rot2) - L*Cos(rot2)*Sin(rot1))*Sqrt(Power(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),2) + 
        Power(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),2)))/
    (Power(L*Cos(rot1)*Cos(rot2) + d2*Cos(rot2)*Sin(rot1) - d1*Sin(rot2),2) + Power(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),
       2) + Power(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),2))
In[49]:= CForm[D[ttht,rot2]]
Out[49]//CForm=
((L*Cos(rot1)*Cos(rot2) + d2*Cos(rot2)*Sin(rot1) - d1*Sin(rot2))*(2*(L*Cos(rot1)*Cos(rot2)*Cos(rot3) + d2*Cos(rot2)*Cos(rot3)*Sin(rot1) - d1*Cos(rot3)*Sin(rot2))*
         (d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3))) + 
        2*(L*Cos(rot1)*Cos(rot2)*Sin(rot3) + d2*Cos(rot2)*Sin(rot1)*Sin(rot3) - d1*Sin(rot2)*Sin(rot3))*
         (d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)))))/
    (2.*Sqrt(Power(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),2) + 
        Power(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),2))*
      (Power(L*Cos(rot1)*Cos(rot2) + d2*Cos(rot2)*Sin(rot1) - d1*Sin(rot2),2) + Power(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + 
          L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),2) + Power(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),2)))
     - ((-(d1*Cos(rot2)) - L*Cos(rot1)*Sin(rot2) - d2*Sin(rot1)*Sin(rot2))*Sqrt(Power(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + 
          L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),2) + Power(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),2)))
     /(Power(L*Cos(rot1)*Cos(rot2) + d2*Cos(rot2)*Sin(rot1) - d1*Sin(rot2),2) + Power(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + 
        L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),2) + Power(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),2))
In[50]:= CForm[D[ttht,rot3]]
Out[50]//CForm=
((L*Cos(rot1)*Cos(rot2) + d2*Cos(rot2)*Sin(rot1) - d1*Sin(rot2))*(2*(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)))*
        (-(d1*Cos(rot2)*Sin(rot3)) + L*(Cos(rot3)*Sin(rot1) - Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(-(Cos(rot1)*Cos(rot3)) - Sin(rot1)*Sin(rot2)*Sin(rot3))) + 
       2*(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)))*
        (d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)))))/
   (2.*Sqrt(Power(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),2) + 
       Power(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),2))*
     (Power(L*Cos(rot1)*Cos(rot2) + d2*Cos(rot2)*Sin(rot1) - d1*Sin(rot2),2) + Power(d1*Cos(rot2)*Cos(rot3) + d2*(Cos(rot3)*Sin(rot1)*Sin(rot2) - Cos(rot1)*Sin(rot3)) + 
         L*(Cos(rot1)*Cos(rot3)*Sin(rot2) + Sin(rot1)*Sin(rot3)),2) + Power(d1*Cos(rot2)*Sin(rot3) + L*(-(Cos(rot3)*Sin(rot1)) + Cos(rot1)*Sin(rot2)*Sin(rot3)) + d2*(Cos(rot1)*Cos(rot3) + Sin(rot1)*Sin(rot2)*Sin(rot3)),2)))