<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD><TITLE></TITLE> <META http-equiv=Content-Type content="text/html; charset=us-ascii"> <META content="MSHTML 6.00.2900.5726" name=GENERATOR></HEAD> <BODY> <P><FONT color=#0000ff>Hi Leen,<BR><BR>I think you mean to write your if-test as follows:</FONT></P> <DIV><FONT size=2>  <FONT face="Courier New">  IF(Q.lt<FONT color=#ff0000>.</FONT>0-0.05.AND.T.eq.1.AND.G.eq.2)THEN</FONT></FONT></DIV> <DIV><FONT size=2></FONT> </DIV> <DIV><FONT color=#0000ff> <DIV><FONT color=#0000ff>(note that the 'lt' comparison operator should be terminated with a '.'. I think this is probably the source of your error.)</FONT></DIV> <DIV><FONT color=#0000ff></FONT> </DIV> <DIV><FONT color=#0000ff>In this case, '0' is a integer, and you're relying the compiler to implicitly cast it as a real. Most compilers will do this reliably, but it's better to retype your '0' as a real:</FONT></DIV></FONT></DIV> <DIV><FONT color=#0000ff></FONT> </DIV> <DIV>    <FONT size=2><FONT face="Courier New">IF ( </FONT></FONT><FONT size=2><FONT face="Courier New">Q .lt. (0.-0.05) .AND.</FONT></FONT></DIV> <DIV><FONT size=2><FONT face="Courier New"> &     T .eq. 1         .AND.</FONT></FONT></DIV> <DIV><FONT size=2><FONT face="Courier New"> &     G .eq. 2               ) THEN</FONT></FONT></DIV> <DIV><FONT face="Courier New" size=2></FONT> </DIV> <DIV><FONT size=2><FONT color=#0000ff size=3>If you're not working with legacy code, please consider using clear variable names so that other developers do not need to guess at the meaning of 'Q', 'T' and 'G'. Hungarian notation can make the type of variables even clearer; when I first read your question, I assumed T must be temperature and therefore a real. You might use a convention like the following:</FONT></FONT></DIV> <DIV><FONT color=#0000ff></FONT> </DIV> <DIV><FONT face="Courier New">Q -> fQHeatFlux</FONT></DIV> <DIV><FONT size=2><FONT face="Courier New" size=3>T -> iType </FONT></FONT></DIV> <DIV><FONT size=2><FONT face="Courier New" size=3>G -> iGSomeOtherName</FONT></DIV><FONT color=#0000ff size=3> <P><FONT color=#0000ff size=3>It seems a little pedantic at first, but I find that once you adapt to Hungarian notation, it's har</FONT><FONT color=#0000ff size=3>d to keep your types straight without it!</FONT></P> <P>Finally, the developer's list is probably a better forum for questions like these. Let me know if you have trouble posting to it.</P> <P><FONT color=#0000ff size=3>Cheers,</FONT></P></FONT> <DIV><FONT color=#0000ff size=3>- Alex</FONT></DIV> <P><FONT color=#0000ff size=3></FONT></P> <P align=left><B><SPAN lang=en-us><FONT face="Times New Roman">Alex Ferguson</FONT></SPAN></B><SPAN lang=en-us><BR><FONT face="Times New Roman">Sustainable Buildings and Communities (Housing Group)<BR>CanmetENERGY<BR>Natural Resources Canada<BR>P:+1 613 995 3294<BR>F:+1 613 996 9909<BR><A href="mailto:Alex.Ferguson@NRCan-RNCan.gc.ca">Alex.Ferguson@NRCan-RNCan.gc.ca</A><BR></P> <P></FONT></SPAN><FONT color=#0000ff size=3></FONT><BR><BR>-----Original Message-----<BR>From: esp-r-bounces@lists.strath.ac.uk [<A href="mailto:esp-r-bounces@lists.strath.ac.uk">mailto:esp-r-bounces@lists.strath.ac.uk</A>] On Behalf Of Leen Peeters<BR>Sent: March 5, 2009 16:38<BR>To: esp-r@lists.strath.ac.uk<BR>Subject: [esp-r] invalid type combination<BR><BR>Dear,<BR><BR>going through the debugger I get the following message<BR><BR><BR>invalid type combination in ordering comparison<BR><BR><BR>when evaluating a case like<BR><BR>IF(Q.lt-0-0.05.AND.T.eq.1.AND.G.eq.2)THEN<BR><BR>where Q is a real and T and G are integers<BR><BR><BR>Can anyone explain me why?<BR>I does not seem to help to add brackets around the value -0.05...<BR><BR>Leen<BR>Disclaimer: <A href="http://www.kuleuven.be/cwis/email_disclaimer.htm">http://www.kuleuven.be/cwis/email_disclaimer.htm</A><BR><BR><BR>_______________________________________________<BR>esp-r mailing list<BR>esp-r@lists.strath.ac.uk<BR><A href="http://lists.strath.ac.uk/mailman/listinfo/esp-r">http://lists.strath.ac.uk/mailman/listinfo/esp-r</A><BR></P></FONT></BODY></HTML>