topic Can I use do loop to calculation pi? in SAS Programming

Can I use do loop to calculation pi?

yuwentaiwan — Sat, 30 May 2020 05:10:55 GMT

I fi pi(=( f(i)+f(i-1) ) /2 )

1 0.263 (0.263+0)/2 (f(0)=0)

2 0.263 (0.263+0.263)/2

3 0.91 (0.91+0.263)/2

4 0.12 (0.12+0.91)/2

5 0.12 (0.12+0.12)/2

Can I use do loop or other method to calculation pi?

Thanks!

Re: Can I use do loop to calculation pi?

Jagadishkatam — Sat, 30 May 2020 05:47:23 GMT

I believe you can achieve the same result without the do loop if you prefer it this way

data have;
input f;
cards;
0.263 
0.263 
0.91  
0.12  
0.12
;
  
data want;
set have;
pi=((f+coalesce(lag(f),0))/2);
run;

Re: Can I use do loop to calculation pi?

ed_sas_member — Sat, 30 May 2020 08:48:10 GMT

Hi @yuwentaiwan

You can use the LAG() function to retrieve the previous value of fi.

The SUM() function is better than the "+" operator in your case as it ignores missing values. So it can easily handle the calculation at the first row, where lag(i) is not defined.

Best,

data want;
	set have;
	pi = sum(fi,lag(fi))/2;
run;

Re: Can I use do loop to calculation pi?

ballardw — Sat, 30 May 2020 12:50:22 GMT

@yuwentaiwan wrote:

I   fi       pi(=( f(i)+f(i-1) ) /2 )

1 0.263    (0.263+0)/2                (f(0)=0)

2 0.263    (0.263+0.263)/2

3 0.91     (0.91+0.263)/2

4 0.12     (0.12+0.91)/2

5 0.12     (0.12+0.12)/2

Can I use do loop or other method to calculation pi?

Thanks!

Is this a programming exercise or do you want to USE the value of pi?

If you need to use pi then you would use the function CONSTANT with 'pi' as the argument.

data junk;
   x=constant('pi');
   put x best16.;
run;

Re: Can I use do loop to calculation pi?

RichardDeVen — Sat, 30 May 2020 15:15:26 GMT

You can use Proc DS2 or FCMP to compute via recursion.

Or try Proc FCMP SOLVE() function