Complex partial fraction

[m_elborolossy]

Hi all
My calc is Nspire cx cas
I try to make a complex partial fraction because the calc make only real one using expand
I try to write a function but there is an error that is not clear to me why
I make the same steps in a Document or scratchpad and work good
Here is my code :

Code: Select all

Define LibPub partialf(expre)=
:Func
:Local ex,r,rc,exc,k,x,kc
:expr("ex(s):="&string(expre))
:r:=polyRoots(getDenom(ex(s)),s)
:exc(s):=ex(s)*s
:rc:=cPolyRoots(getDenom(exc(s)),s)
:k(s):=((getNum(ex(s)))/(2*s*imag(rc[2])*i))
:kc:=k(rc[2])
:Return kc
:EndFunc

This is only the start and i assume that the i have a real root (s = 0) and two conj complex roots s={(-a+b*i),(-a-b*i)}
The error in this line : kc:=k(rc[2])

[Bisam]

I spotted a possible (and quite usual) problem.

When you create a function by using f(s):= anything, the right member is NOT evaluated.
It will only be evaluated when you will use the function and replace the value of "s" by any expression.

At this time, the calc may see an error such as a "division by zero" that couldn't be seen earlier.
I think that, in your case, exc(s) still has zero as a root of denominator... or something like that.

Did you try to "disp" some intermediate results to spot the problem more precisely ?
And what is the error returned ?

[m_elborolossy]

Thanks Bisam
I think it works now good
When I finish it i will upload it
This is the updated code :

Code: Select all

Define LibPub partialf(expre)=
Func
:Local ex,r,rc,exc,k,x,kc
:expr("ex(s):="&string(expre))
:r:=polyRoots(getDenom(ex(s)),s)
:expr("exc(s):="&string(ex(s)*s))
:rc:=cPolyRoots(getDenom(exc(s)),s)
:expr("k(s):="&string(((getNum(ex(s)))/(2*s*imag(rc[2])*i))))
:kc:=k(rc[2])
:Return kc
:EndFunc

[Bisam]

Nice !
Glad to have helped... and thankful for having talked with someone who knows how to program decently !

[jmat]

wonderful !!We hope this program

[Bisam]

Uh ?
Seems to be an early posting...

[mike martin]

Hi there,
Did you ever finish the code for this? If so, is there somewhere I can download it?

I really need something like this on my nspire.

Thanks
Mike

[Bisam]

Just try to create it yourself by copying the code which is on the 3rd post.

[endothes]

When I use the code in the third post with a function such as:

(0.4)*(s-1500)/(s^2+1000*s+1.25*10^6)

I get too many arguments error. Does the program listed above work for anyone else?

[Hisham]

When I use the code in the third post with a function such as:

(0.4)*(s-1500)/(s^2+1000*s+1.25*10^6)

I get too many arguments error. Does the program listed above work for anyone else?

http://www.allcalc.tk/10272 (PFE)
http://www.allcalc.tk/4982 (PFE + inverse L-Transformation)

Best,

Hisham