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Other Program Statements with PROC NLIN

Several SAS program statements can be used after the PROC NLIN statement. These statements can appear anywhere in the PROC NLIN statement, but new variables must be created before they appear in other statements. For example, the following statements are valid since they create the variable temp before they use it in the MODEL statement:

   proc nlin;
      parms b0=0 to 2 by 0.5 b1=0.01 to 0.09 by 0.01;
      temp=exp(-b1*x);
      model y=b0*(1-temp);

The following statements result in missing values for y because the variable temp is undefined before it is used:

   proc nlin;
      parms b0=0 to 2 by 0.5 b1=0.01 to 0.09 by 0.01;
      model y=b0*(1-temp);
      temp=exp(-b1*x);

PROC NLIN can process assignment statements, explicitly or implicitly subscripted ARRAY statements, explicitly or implicitly subscripted array references, IF statements, SAS functions, and program control statements. You can use program statements to create new SAS variables for the duration of the procedure. These variables are not permanently included in the data set to which PROC NLIN is applied. Program statements can include variables in the DATA= data set, parameter names, variables created by preceding program statements within PROC NLIN, and special variables used by PROC NLIN. All of the following SAS program statements can be used in PROC NLIN:

• ARRAY
• assignment (y = a*x + b;)
• CALL
• DO
• iterative DO
• DO UNTIL
• DO WHILE
• END
• FILE
• GO TO
• IF-THEN/ELSE
• LINK-RETURN
• PUT (defaults to the list)
• RETURN
• SELECT
• sum (y + 1;)

These statements can use the special variables created by PROC NLIN. Consult the section "Special Variables" for more information on special variables.

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