Calculating RSI for todays prices

[torebecca@xxxx]

Is it possible to write an example ( or by some other means ) to be 
able to calculate the updated rsi value for a stock on say a 
theoretical/intra-day price. I know I can manually enter an intra-
day quote for a stock and then view the updated rsi value, but is 
there any other way i can do this ?

IE. If i was using a period of 14, to use the last 13 closes and a 
theoretical close ( intra-day quote ) to calculate the rsi ?

Thanks for your help