Subject: spread option code change
zhiyang and zhiyun ,
vince told me that london has some trouble to calculate spread option
for correl = 1 , voll = vol 2 . in such a case , the effective volatility becomes
zero , and the option has zero time value .
i have modified the unitcorrpremium ( ) routine to force the code to treat
this situation as a special case . ( it returns the discounted intrinsic value ) .
please incorporate this chang to your code so that it will no longer cause
any
problems that should not happen in the first place .
if you have any questions , please let me know .
zimin
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double unitcorrpremium (
double sl ,
double s 2 ,
double strike ,
double r ,
double ql ,
double q 2 ,
double voll ,
double vol 2 ,
double correl ,
double tmat ,
int opttype
)
{
double retval ;
if ( tmat < = 0 . 0 )
return intrinsic ( sl , s 2 , strike , opttype ) ;
/ / look right here for the change , only two lines .
if ( ( 1 . 0 - correl ) < tiny &
setup ( sl , s 2 , strike , r , ql , q 2 , voll , vol 2 , correl , tmat ) ;
if ( opttype )
retval = s . disc * gauherint ( ffuncoc ) / sqrtpi ;
else
retval = s . disc * gauherint ( ffuncop ) / sqrtpi ;
return retval ;
}