This is an old version, view current version.

## 26.4 Digamma

The digamma function $$\Psi$$ is the derivative of the $$\log \Gamma$$ function, $\Psi(u) \ = \ \frac{d}{d u} \log \Gamma(u) \ = \ \frac{1}{\Gamma(u)} \ \frac{d}{d u} \Gamma(u).$
{"ft_lang_label":"__label__en","ft_lang_prob":0.61742383,"math_prob":0.9999546,"size":424,"snap":"2022-40-2023-06","text_gpt3_token_len":158,"char_repetition_ratio":0.18571429,"word_repetition_ratio":0.7878788,"special_character_ratio":0.4268868,"punctuation_ratio":0.0875,"nsfw_num_words":0,"has_unicode_error":false,"math_prob_llama3":1.0000074,"pos_list":[0],"im_url_duplicate_count":[null],"WARC_HEADER":"{\"WARC-Type\":\"response\",\"WARC-Date\":\"2022-10-04T13:29:00Z\",\"WARC-Record-ID\":\"<urn:uuid:3bbb684e-e98b-4078-849b-13e90ba64f35>\",\"Content-Length\":\"86849\",\"Content-Type\":\"application/http; msgtype=response\",\"WARC-Warcinfo-ID\":\"<urn:uuid:604c4b32-61a7-46e5-9f23-0510b9086b37>\",\"WARC-Concurrent-To\":\"<urn:uuid:11bd942d-d044-414b-9adc-f556bce26c7d>\",\"WARC-IP-Address\":\"185.199.108.153\",\"WARC-Target-URI\":\"https://mc-stan.org/docs/2_20/functions-reference/digamma-appendix.html\",\"WARC-Payload-Digest\":\"sha1:GHC7U6YANUJY2QV77UWAQGLF6KMF5ZQ6\",\"WARC-Block-Digest\":\"sha1:BEHIZ7RBCCT6CPAZHSFFQMLHNO7EM4K7\",\"WARC-Identified-Payload-Type\":\"application/xhtml+xml\",\"warc_filename\":\"/cc_download/warc_2022/CC-MAIN-2022-40/CC-MAIN-2022-40_segments_1664030337504.21_warc_CC-MAIN-20221004121345-20221004151345-00635.warc.gz\"}"}