Yes,progression is based on this method.
If you want to calculate the accurate house cusps,you ,first,need to calculate
the true arc of that day,and plus the arc to the MC, and according to the
longitude and latitude you calculate new house cusps.That is the exact method.
For example,if one is born at am 0:0 on Jan 1st,2000 and we want to cast his
progression chart on 2000,Jul 1st.then it is WRONG to cast it by calculating the proportion of the days in a year and apply it to the "one day to one year symbolic system" and erect it with the obtained time.(Sorry,the computer I use now doesn't support my favorite Chinese input serveice.So,I cannot give more detail descriptions due to my poor English.)
A simple way to check if your progression chart is valid is that,you examine
the Ascedant to see if it goes forward exceed 2 degrees per year.
If you cannot understand me prcisely,it is ok. You can cast it as I stated before.That is,even if you want to cast a progression chart in the middle of a
year,you just approximate it to the birthday of that year.The astrologer will
by himself estimate the error between the approximated chart and exact one.
By the way,can you implement the forward progression and reverse one?
That's all
Sincerely
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om a vam ram ham kham om a vi ra hum kham om a ra pa ca na 紫微神咒
星平透壬穿禽網站我的FB網頁om namo manjusriye namah susriye nama uttama sriye svaha
namah saddharma pundarika sutra svaha namah Suvarṇaprabhāsottamasūtrendrarājaḥ svaha namo Mahamayuri Vidyarajni Sutra namo Karunikarāja Rāṣṭrapāla Prajñāpāramitā sūtra namo Caturmahārājakayikas om a hum om a vam ram ham kham a vi ra hūm kham a ra pa ca na om alolik svaha om gagana sambhava vajra hoh om trum svaha Taiwan Love & Peace
禮敬諸佛 稱讚如來
廣修供養 懺悔業障
隨喜功德 請轉法輪
請佛住世 常隨佛學
恒順眾生 普皆回向
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每自作是意 以何令眾生
得入無上慧 速成就佛身
--妙法蓮華經