The following is taken from a mainstream book on financial derivatives.
"The price of currency A expressed in terms of the price of currency B follows the process
dS=(rB-rA)S*dt+sigma*S*dt
where rA is the risk free interest rate in currency A, and rB is the risk free interest rate in currency B"
I am a little bit confused here. When rB > rA, the price of currency A goes up? I thought that when the difference in interest rate is positive, the currency where the interest rate is high goes up.
I greatly appreciate your help.