Tony Hutchins has posted some very compact versions of the Black-Scholes formula. This version is just a modification of Tony's previous work and ideas. The HP 17BII+ does not have L() and G() functions, and Tony has posted a version which cleverly uses intermediate variables. I liked his work so much that I decided to modify it a little. This version uses just one intermediate variable named "SOLVE", the user will presented with SOLVE, CALLV, and PUTV on the second page of variables. Hitting SOLVE would seem intuitive, and the user just has to remember to explicitly solve for CALLV before solving PUTV.

Thanks, Tony!

Bob Wang

BLK.SCHLS.TONY:

0×(PS+PE+RF%+T+S)

+IF(S(SOLVE):SOLVE-(LN(PS÷PE)+(RF%÷100+S^2÷2)×T)÷S÷SQRT(T):

IF(S(CALLV):CALLV-PS×ABS(

IF(SOLVE<0:0:-1)+EXP(-(SOLVE^2)÷2)

×((187÷(1+ABS(SOLVE)÷3.006)-24)

÷(1+ABS(SOLVE)÷3.006)+87)

÷(1+ABS(SOLVE)÷3.006)÷500)

+PE×EXP(-RF%×T÷100)×ABS(

IF(SOLVE-S×SQRT(T)<0:0:-1)+EXP(-((SOLVE-S×SQRT(T))^2)÷2)

×((187÷(1+ABS(SOLVE-S×SQRT(T))÷3.006)-24)

÷(1+ABS(SOLVE-S×SQRT(T))÷3.006)+87)

÷(1+ABS(SOLVE-S×SQRT(T))÷3.006)÷500):

PUTV-CALLV+PS-PE×EXP(-RF%×T÷100))