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Date:         Mon, 3 May 2010 10:15:32 -0400
Reply-To:     "P. Cristian Gugiu" <crisgugiu@YAHOO.COM>
Sender:       "SAS(r) Discussion" <SAS-L@LISTSERV.UGA.EDU>
From:         "P. Cristian Gugiu" <crisgugiu@YAHOO.COM>
Subject:      Help with macro variables

Hi all. I wrote code for calculating a double integral using the Trapezoid Rule. However, I need to pass a value out of the macro and keep running into problems. Can someone tell me how I can assign the value for the variable "Volume" to a macro variable that I can use outside of the macro.

Thanks, Cristian

%Let Pi=3.1415926535897932384626433832795; %Macro Trapezoid(minX=,maxX=,minY=,maxY=,func=,lbl=); %Global mu; data _NULL_; delta=.1; dx=delta; dy=delta; sum=0; do x=&minX to &maxX by dx; if round(x,dx) eq &minX OR round(x,dx) eq &maxX then mX=1; else mX=2; do y=&minY to &maxY by dy; if round(y,dy) eq &minY OR round(y,dy) eq &maxY then mY=1; else mY=2; sum=sum + mX*mY*(&func); end; end; Volume=round(0.25*dx*dy*sum,.00000001); %let mu= input(Volume,best4.); put "&lbl=" Volume; %put &mu; run;quit; %Mend Trapezoid; %let mu1=29.9924961; /* Mean of X */ %let var1=23.2736469; /* Variance of X */ %let mu2=9.99274913; /* Mean of Y */ %let var2=0.24619424; /* Variance of Y */ %let rho=0.75046; /* Correlation b/w X and Y */

%let g_xy=(sqrt(abs(x*y))); /* Function */ %let pdf = (1/(2*&Pi*sqrt(&var1*&var2*(1-&rho**2))))*exp(-(1/(2*(1- &rho**2)))*(((x-&mu1)**2)/&var1 + ((y-&mu2)**2)/&var2 - 2*&rho*(x-&mu1)*(y- &mu2)/sqrt(&var1*&var2)));

/* Estimate mean of E(Z)=E[g(X,Y)] */ %let function=&g_xy * &pdf; %Trapezoid(minX=-100,maxX=100,minY=-100,maxY=100,func=&function,lbl=Mean);


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