eval(h) with division inside divisor

[fjleon]

Hello people. I found an issue when making a calculation that should work OK. I have fixed it already but was wondering why this happens:

XMONOBJ and XMONTOPROV are 15 2
IVA is 5 2

EVAL(H) XMONOBJ=XMONTOPROV/(1+(IVA/100);

This calculation makes eval(h) truncate all decimals. Even trying 1.00 and 100.00 truncates all decimals.
I had to split the divisor into another variable:
PORCIVA=1+(IVA/100)
EVAL(H) XMONOBJ=XMONTOPROV/PORCIVA;

is there any way i can fool RPG into calculating what i want without doing the split? My guess is that 1+(IVA/100) is being calculated internally with a different size therefore eval(h) does not do what i expect it to do.

By the way, what i am trying to do is that i have a number with an added 12% and i want to substract that value to obtain the original number. IE i have 15.10 and i need to obtain 13.48

[jamief]

Re: eval(h) with division inside divisor

lose that wacky eval ..

XMONOBJ=%dech(XMONTOPROV/(1+(IVA/100)):15:5); 

[fjleon]

Re: eval(h) with division inside divisor

lose that wacky eval ..

XMONOBJ=%dech(XMONTOPROV/(1+(IVA/100)):15:5); 

i love this forum! thanks, already tested it.

[jamief]

Re: eval(h) with division inside divisor

and the forum loves you back!

[JonBoy]

Re: eval(h) with division inside divisor

lose that wacky eval ..

XMONOBJ=%dech(XMONTOPROV/(1+(IVA/100)):15:5); 

This will work in this instance, but RPG has an "engineered" approach to this that avoids the use of the BIF. I haven't time to check it but I'm also pretty certain that the %DEC BIF approach will not always work.

The "RPG Way" would be to use the op-code extender R on the Eval

EVAL(RH) XMONOBJ=XMONTOPROV/(1+(IVA/100);

The idea behind the R is to tell RPG that when calculating the size of the intermediate result it should never let the number of decimal places fall below the number needed to create the final result. That is probably an easier generic approach as you never need to work out at what point the %dec needs to be inserted to guarantee the desired approach.

[bryce4president]

Re: eval(h) with division inside divisor

Great tip Jon. I had forgotten about that. As I program in /free I don't usually think about opcode extenders for eval. Maybe if they had an H spec that forced this... say maybe something like....

     H EXPROPTS(*RESDECPOS)

Put this at the top of your source member and forget about opcode extenders