I'm having a problem with summation.

I am comparing the area calculation with a known solution. First I use sum. The result is incorrect.



So I check it using a different method. Result is correct.



Check against an Excel solution. Result is correct.



Am I misinterpreting the sum function?

https://smath.com/wiki/GetFile.aspx?File=forum_attach%2fTheWizEd%2fsectionprop.zip

Hello Ed,

I think there is a bug in the summation operator.
[LIVE width=445 height=214]http://smath.info/live/?file=2123[/LIVE]
These two results should be the same, but they are not. I can not figure out how the summation operator get that number?
Here is another example - I am also puzzled here???
[MATH=eng]t←mat(2,5,1,2,2,2)[/MATH]
[MATH=eng]el(t,1,1)*el(t,2,2)-el(t,2,1)*el(t,1,2)=-1[/MATH]
[MATH=eng]sum((el(t,1,1)*el(t,2,2)-el(t,2,1)*el(t,1,2)),n,1,1)=3[/MATH]

Regards,
Radovan

Radovan,

Thanks for the help.

I can get around it by a user function for now.

Ed