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## Re: Octave-symbolic package

 From: Donald MacKinnon Subject: Re: Octave-symbolic package Date: Sun, 22 Mar 2009 12:23:49 +0000 User-agent: Thunderbird 2.0.0.19 (X11/20090114)

```Benjamin Brown wrote:
```
```Hello,

```
I come from a Matlab background, but I've been trying to migrate to octave. The most important thing that I've been missing is the symbolic toolbox. Then I found octave-symbolic. The only issue I'm having is that the usage seems to be a bit different from the Matlab toolbox. I've defined a number of symbols, z, z_p, b, and a using:
```
z=sym("z")
z_p=sym("z_p")...

without error.  Then when I try to create an expression:

k=e^(i*b(sqrt((z-z_p)^2+a^2)))/(4*pi*sqrt((z-z_p)^2+a^2))

I get the following errors:

error: mapper: wrong type argument `ex'
error: evaluating argument list element number 1
error: evaluating binary operator `*' near line 11, column 7
error: evaluating binary operator `^' near line 11, column 4
error: evaluating binary operator `/' near line 11, column 31
error: evaluating assignment expression near line 11, column 2

```
Is there any way you could send me some basic usage sample code for this package. Any help would be appreciated.
```
-Benjamin Brown

Hello Ben,
```
It may or may not help but if you look at the the website octave.sourceforge.net/doc/funref_symbolic.html it list some routines which test for the variable type in use etc. Now knowing the type of variable or function you are dealing with, may guide you towards what is wrong. For example "wrong type argument `ex'". Now the funref_symbolic.html page gives you a test for the type 'ex', i.e. is_ex. This helped me but it didn't solve my problem. Mine I think was that an array was expected but when the routine was given an array it still objected. Perhaps octave symbolic can't handle arrays yet.
```
I hope the above helps you.
Donald

```
```
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