Determine if connections to FRED data servers are valid
x = isconnection(c)
FRED® connection object created with
x = isconnection(c) returns
= 1 if a connection to the FRED data server is valid,
x = 0 otherwise.
Establish a connection
c to a FRED data
c = fred('https://research.stlouisfed.org/fred2/')
c is a valid connection.
x = isconnection(c) x = 1