https://communities.sas.com/t5/ODS-and-Base-Reporting/Problems-about-take-logarithm-in-two-obs-in-single-variable/m-p/1793#M799 Can anyone suggest the method for me to me to take logarithm on divided of two observation, e.g. log(VariableX<N>/VariableX[n+1])that like Excel? <BR /> Example, =log(A10/A11).<BR /> My Constraint is huge amount of data that cannot process in Excel.</N> Fri, 17 Nov 2006 07:40:39 GMT deleted_user 2006-11-17T07:40:39Z https://communities.sas.com/t5/ODS-and-Base-Reporting/Problems-about-take-logarithm-in-two-obs-in-single-variable/m-p/1793#M799 Can anyone suggest the method for me to me to take logarithm on divided of two observation, e.g. log(VariableX<N>/VariableX[n+1])that like Excel? <BR /> Example, =log(A10/A11).<BR /> My Constraint is huge amount of data that cannot process in Excel.</N> Fri, 17 Nov 2006 07:40:39 GMT https://communities.sas.com/t5/ODS-and-Base-Reporting/Problems-about-take-logarithm-in-two-obs-in-single-variable/m-p/1793#M799 deleted_user 2006-11-17T07:40:39Z https://communities.sas.com/t5/ODS-and-Base-Reporting/Problems-about-take-logarithm-in-two-obs-in-single-variable/m-p/1794#M800 This question is perhaps best answered by Technical Support. You can enter it online at <A href="http://support.sas.com/ctx/supportform/index.jsp" target="_blank">http://support.sas.com/ctx/supportform/index.jsp</A> .<BR /> <BR /> -- David Kelley, SAS Tue, 21 Nov 2006 14:34:49 GMT https://communities.sas.com/t5/ODS-and-Base-Reporting/Problems-about-take-logarithm-in-two-obs-in-single-variable/m-p/1794#M800 David_SAS 2006-11-21T14:34:49Z https://communities.sas.com/t5/ODS-and-Base-Reporting/Problems-about-take-logarithm-in-two-obs-in-single-variable/m-p/1795#M801 In SAS, you can't read the value of the next line... but you can use the value of the previous line.<BR /> So in a Data step, compute a new variable, the formula of which will be :<BR /> LOG(LAG(X)/X) ;<BR /> <BR /> The LAG function returns the value for variable X on the previously read observation. Thu, 23 Nov 2006 14:50:31 GMT https://communities.sas.com/t5/ODS-and-Base-Reporting/Problems-about-take-logarithm-in-two-obs-in-single-variable/m-p/1795#M801 Olivier 2006-11-23T14:50:31Z