सिद्धान्तशिरोमणि: गणिताध्याय (भास्कराचार्य - ग्रहगणित, मध्यमाधिकार व स्पष्टाधिकार सटीक)

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in the east, thus rising heliacally. After attaining the
maximum elongation in his retrograde motion, his motion
will then become direct, so that he again approaches the
Sun, going from west to east. Next a little before
overtaking the Sun, he sets heliacally in the east, and
thereafter, having overtaking the Sun, he rises heliacally
in the west.
Here, one point is to be mentioned. The time between
Mercury's maximum elongation in the west and again the
maximum elongation in the east (which are termed
maximum eastern elongation and maximum western
elongation with respect to the Sun) will be far less than
the time between the maximum elongation in the east
(ie. maximum western elongation with respect to the Sun)
and that in the west (ie. maximum western elongation
with respect to the Sun) in as much as when Mercury is
retrograde, and the Sun having always direct motion, the
relative velocity will be the sum of the retrograde velocity
of Mercury and the direct velocity of the Sun.
In the case of the superior planets, as mentioned
above, the superior planets set heliacally in the west and
rise heliacally in the east. They will not rise heliacally
in the west and will not set heliacally in the east which
happens only if either the superior planet has a greater
velocity than the Sun or the Sun has a retrograde motion
which is never the case.
Verse 5. Speciality with respect to Mercury and
Venus.
Mercury and Venus rise heliacally in the west in their
direct motion, (attain maximum elongation before they)
become retrograde, set heliacally there itself, then rise
heliacally in the east continuing to be retrograde, (attain
maximum elongation there before they) next become direct