how to get the names of week day in fast formula

Summary:

I need to get the Name of the day based on date.

Content (please ensure you mask any confidential information):

I need to get the Name of the day based on date, to be used in "Global Absence Entry Validation" formula.

for example, I need to check the name of the day i.e. Sunday, Monday…. etc. base on Start date of absence, I used the functions TO_TEXT(IV_START_DATE,'DAY'), TO_CHAR(IV_END_DATE,'DAY') , TO_TEXT(IV_START_DATE,'DY'), TO_CHAR(IV_END_DATE,'DY'), but instead of returning the name of day it returns the number of day of week i.e. 1,2,3,4,5,6,7