ऋतश्च

The reduplicate of a root which ends in short ऋ gets, in the Intensive without यङ् the above augments (1. रीक् 2. रुक् and 3. रिक्), 1. रि 2. र् and 3. रि।
Karika:-

किरतिं चर्क्करीतान्तं पचतीत्यत्र यो नयेत् ।
प्राप्तिज्ञं तमहं मन्ये प्रारब्धस्तेन संग्रहः ॥

Thus चकर्ति, चरिकर्ति and चरीकर्ति, जर्हर्ति, जरिहर्ति and जरीहर्ति ॥ Why do we say 'which ends in a short ऋ'? The rule does not apply to roots ending in long ॠ as, चाकर्ति, चाकीर्तः, चाकिरति from कॄ ॥ The word ऋतः qualifies the word अङ्ग and not the word अभ्यास, for an abhyasa is always short, so the त् in ऋत् would become meaningless if the word qualified reduplicate. Therefore कॄ ending in long ॠ does not get रि, र् and रि augments in the reduplicate.

Karika:- He who can conjugate, in the Present tense, the yan-luk Intensive of कॄ and of other roots ending in long ॠ, is considered by me to be a person who has attained to the right knowledge of the employment of the augments र्, री, रि &c: and he has obtained the right use of words.

The word किरति in the Karika is illustrative of all roots like कॄ (किरति) ending in long ॠ ॥ चर्क्करीत is the name given to the यङ् लुक् form of the Intensive, by ancient grammarians. चर्क्करीतान्त means, therefore, a form ending in yan-luk. पचति is illustrative of लट् or Present tense.