(12C) Actuarial Calculations

[Dieter]

(05-12-2018 05:41 AM)Gamo Wrote:  *Program to calculate [i] and use fractional [n]

This seems to be a Newton-style solver that calculates the interest rate iteratively. This requires the usual convergence check: exit if the absolute value of the last change in i is less than 1E–8. Now take a look at line 53...56: here the HP programmer found a nice way to determine the absolute value of x.

Code:

53 ENTER
54 CHS
55 X≤Y
56 X<>Y

Compared with the common method (calculate √x²) this has three advantages: there are no roundoff errors, LastX is preserved and it also works for x ≥ 1E+50.

(05-12-2018 05:41 AM)Gamo Wrote:  Remark:
All calculations above work on HP 15C using TVM program from the Advance Functions Handbook.

Just to be clear – I assume what you want to say is this:

Unlike the 12C, the TVM program in the 15C Advanced Functions Handbook does not round n to the next higher integer, it directly returns a fractional results if required. So the above programs are not needed there.

Dieter