I am using latex to write a mathematically dense document which has several hundred differential forms and products. There must be better ways than just typing out the whole equations line by line. Can any body suggest me some better productivity techniques which could reduce some of the work of debugging some of the equations.
I am pasting a part of equations which I have to write.
\begin{equation}
\begin{aligned}
Energy^{(i)} & = U^{(i)}_{1} + U^{(i)}_{2} + U^{(i)}_{3}\\
U^{(1)}_{1} & = \int_{a}^{b} \int_{0}^{\sigma_{rr}^{(1)}} \Big(\frac{(1+\nu)(\sigma_{rr}^{(1)})}{E1} - \frac{\nu (2(\sigma_{rr}^{(1)})+ \sigma_{z})}{E1} \Big) d(\sigma_{rr}^{(1)}) r dr dz \\
U^{(1)}_{2} & = \int_{a}^{b} \int_{0}^{\sigma_{rz}^{(1)}} (1+\nu)\frac{(\sigma_{rz}^{(1)})}{E1} d(\sigma_{rz}^{(1)}) r dr dz \\
U^{(1)}_{3} & = \int_{a}^{b} \int_{0}^{\sigma_{zz}^{(1)}} \Big(\frac{(1+\nu)\sigma_{zz}^{(1)}}{2E1} - \frac{\nu ((\sigma_{zz}^{(1)})+ 2\sigma_{rr}^{(1)})}{2 E1} \Big) d(\sigma_{zz}^{(1)}) r dr dz \\
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% End of 1
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U^{(2)}_{1} & = \int_{b}^{c} \int_{0}^{\sigma_{rr}^{(2)}} \Big(\frac{(1+\nu)(\sigma_{rr}^{(2)})}{E2} - \frac{\nu (2(\sigma_{rr}^{(2)})+ \sigma_{z})}{E2} \Big) d(\sigma_{rr}^{(2)}) r dr dz \\
U^{(2)}_{2} & = \int_{b}^{c} \int_{0}^{\sigma_{rz}^{(2)}} (1+\nu)\frac{(\sigma_{rz}^{(2)})}{E2} d(\sigma_{rz}^{(2)}) r dr dz \\
U^{(2)}_{3} & = \int_{b}^{c} \int_{0}^{\sigma_{zz}^{(2)}} \Big(\frac{(1+\nu)\sigma_{zz}^{(2)}}{2E2} - \frac{\nu ((\sigma_{zz}^{(2)})+ 2\sigma_{rr}^{(2)})}{2 E2} \Big) d(\sigma_{zz}^{(2)}) r dr dz \\
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% End of 2
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U^{(3)}_{1} & = \int_{c}^{d} \int_{0}^{\sigma_{rr}^{(3)}} \Big(\frac{(1+\nu)(\sigma_{rr}^{(3)})}{E3} - \frac{\nu (2(\sigma_{rr}^{(3)})+ \sigma_{z})}{E3} \Big) d(\sigma_{rr}^{(3)}) r dr dz \\
U^{(3)}_{2} & = \int_{c}^{d} \int_{0}^{\sigma_{rz}^{(3)}} (1+\nu)\frac{(\sigma_{rz}^{(3)})}{E3} d(\sigma_{rz}^{(3)}) r dr dz \\
U^{(3)}_{3} & = \int_{c}^{d} \int_{0}^{\sigma_{zz}^{(3)}} \Big(\frac{(1+\nu)\sigma_{zz}^{(3)}}{2E3} - \frac{\nu ((\sigma_{zz}^{(3)})+ 2\sigma_{rr}^{(3)})}{2 E3} \Big) d(\sigma_{zz}^{(3)}) r dr dz \\
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% End of 3
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\end{aligned}
\end{equation}