topic Re: Solving for x and putting that result in a variable? in SAS Programming

Solving for x and putting that result in a variable?

mitrakos — Tue, 04 May 2021 17:15:32 GMT

Hi Everyone,

I have a dataset where I am trying to solve for X and then put that X value in a new variable. Below is a sample, with the missing value being X.

data sample;
input A S P C B;
datalines;
200 100 200 50 .
;
run;

The equation is: A = (S + P) - (C + B).

In this example, B is the X we're solving for. We know that B = 50 in this case since it's a simple equation but the real dataset has thousands of rows and more complicated numbers unfortunately. Is there any way I can have SAS solve for B, and then put that value of B on a new variable?

Thank you so much!

Re: Solving for x and putting that result in a variable?

Tom — Tue, 04 May 2021 17:29:29 GMT

Are you asking for SAS to convert the assignment statement.

A = (S + P) - (C + B);

Into an assignment statement with B as the target?

Why not just perform the re-write yourself?

* start :
A = (S + P) - (C + B);
* remove () ;
A = S + P - C - B;  
* add B to both sides ;
A+B = S + P - C ;
* subtract A from both sides;
B = S + P - C - A;

If your real problem is more complex then perhaps you need PROC IML or PROC NLIN?

Re: Solving for x and putting that result in a variable?

mitrakos — Tue, 04 May 2021 17:29:56 GMT

Oh god I was so caught up in trying to solve for x using the formula given to me I didn’t even think about rewriting it. I’m so dumb. Thank you so much!!