how to convert julian day to normal date in txt file (2017 1 20)

Hello, please, I would like to know if you have knowledge of how to be able to read a .SAC file with date format in Julian numbering or Julian day to convert it into a standard.txt date. Example:

* Julian day RP.PTP .--. HHZ.D.2015.038.223131.SAC

* on file 2014 1 2 1930 51.5

What I am looking for is that the code does a search within the SAC and relates it to the date of the txt to extract information

[Walter Roberson]

https://www.mathworks.com/matlabcentral/answers/1303-convert-julian-date-to-calendar-days#answer_359958

https://www.mathworks.com/matlabcentral/fileexchange/46356-rdsac-and-mksac-read-and-write-sac-seismic-data-file

[Daphne Sagel Aguilar]

thanks you