Bonds

[salvomic]

dear Randal,
thank you for your report.
You're right, there are some (and not good) approximations in my program. I made it in 2015 and it seemed to work well then, but now I can see your observed differences.
I don't know if the problem stay in the new firmware or in my formulas. For example the use of solve() function like this code:

Code:

C:= coupon; A:= ann; Y:= years; P:= price;
  // yield := Solve.SOLVE((C/A)*( (1-1/(1+(X/A))^(A*Y)) / (X/A) ) + 100/(1+(X/A))^(A*Y) = P, X);
  yield := FNROOT((C/A)*( (1-1/(1+(X/A))^(A*Y)) / (X/A) ) + 100/(1+(X/A))^(A*Y) = P, X);

I hope someone could be so kind to help us to find the bug.

73, regards
salvo it9clu

EDIT (PS): maybe sometime HP could implement such function inside the standard APPs in the Prime. I'm looking forward :-) ;-)