Hello,

I bought some weeks ago the hp41 structural analysis pac and i am very happy about it.

I was porting the equations used in the manual to my hp49g+ but i am having an issue with a formula. I am asking to other mechanical engineers or mathematicians if they did it with success.

The formula i am referring to has been extracted from Felix Wojiechowski book, properties of plane cross sections, machine design, p. 150, jan 22, 1976.

Given the coordinates of a section i would like to calculate the product of inertia Ixy.

The formula starts like this:

Sum for i=0 to N where N is the number of coordinates for

1

----------- * [ 1/8*(........)]

(xi+1 - xi)

It is obvious that if xi+1 and x1 are the same (vertical points) the division leads to infinite.

The hp-41 with the ROM does not stop because of this issue...

Any help is apreciated,

Thanks

Giancarlo