matu̐p

The matu̐p-pratyaya creates common words like hanumān and bhagavān. It has many specific use cases, but here is the general pattern:

• तदस्यास्त्यस्मिन्निति मतुप्। ५.२.९४
  tadasyāstyasminniti matup (5.2.94)
  tat asya asti asmin iti matu̐p
  [The taddhita-pratyaya] matu̐p [is optionally introduced after a prātipadika or the ṅī and āp pratyayas after a term denoting] that which one possesses or contains.

Sound changes

matu̐p generally causes no sound changes. The major exception is that mat becomes vat when it follows certain sounds.

Here is the specific rule from the asiddha section of the Aṣṭādhyāyī:

• मादुपधायाश्च मतोर्वोऽयवादिभ्यः। ८.२.९
  mādupadhāyāśca matorvo'yavādibhyaḥ (8.2.9)
  m-āt upadhāyāḥ ca matoḥ vaḥ a-yavādibhyaḥ
  After the sounds m, a, and ā, even if penultimate, [the first letter of the pratyaya] matu̐ becomes v if not following an item in the list beginning with yava.

And some examples:

• भग + मत् → भगवत्
  bhaga + mat → bhagavat
  (final a)
  

• लक्ष्मी + मत् → लक्ष्मीवत्
  lakṣmī + mat → lakṣmīvat
  (penultimate m)
  

Sample prakriyās

With mat:

1. mati1.2.46 kṛttaddhitasamāsāśca
2. matimat5.2.94 tadasyāstyasminniti matup

With vat and a penultimate a:

1. yaśas1.2.46 kṛttaddhitasamāsāśca
2. yaśas mat5.2.94 tadasyāstyasminniti matup
3. yaśasvat8.2.9 mādupadhāyāśca matorvo'yavādibhyaḥ

With vat and a final a:

1. bhaga1.2.46 kṛttaddhitasamāsāśca
2. bhaga mat5.2.94 tadasyāstyasminniti matup
3. bhagavat8.2.9 mādupadhāyāśca matorvo'yavādibhyaḥ