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I'm trying to solve positions of the planets as described in this paper.

Step 3 of the computation starts with "Modulus the mean anomaly so that $-180^o \lt M \lt +180^o$." I understand what that means (we're constraining M to be from $-180^o$ to $180^o$), but the exact mathematical operations to perform here elude me.

This is an easy problem if the output range is zero to positive whatever, but given the low end of the range is a negative number, I'm thrown for a loop. Can anyone bail me out here please?

iadvd
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Matthew
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    Add or subtract an appropriate multiple of $360^{\circ}$ such that the result is in the desired range. – hmakholm left over Monica Jun 14 '15 at 20:49
  • Start with a typical modulus of $360$, so you get values in $[0^\circ,359^\circ]$. For every value $\ge180^\circ$, subtract $360^\circ$ so that that the final result is in the desired range. – abiessu Jun 14 '15 at 21:36

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