Units cancel problem in symbolic functions

[McHale-disabled]

Hi,



I am using units in polylog functions that should cancel out. It seems, as if this does not work. Can I force Mathcad to cancel the units?



Please see the attached file.



Regards,

Martin

[Luc_Meekes-disa]

Martin,

1. You forgot to attach. If you do so (you can edit your own posts, so you do not even have to reply), attach a Mathcad version 11 (or earlier) .MCD file for a broad audience.

2. Mathcad's symbolic processor is rather different from its numeric processor. While the numeric processor interprets units, the symbolic processor just treats them as symbols. It doesn't "know" e.g. that Newton (N) is kg*m/s^2.

Success!
Luc

[ptc-1368288]

On 9/21/2009 1:05:47 PM, McHale wrote:
>Hi,
>
>I am using units in polylog
>functions that should cancel
>out. It seems, as if this does
>not work. Can I force Mathcad
>to cancel the units?
>
>Please see the attached file.
>
>Regards,
>Martin
_____________________________

Polylog is a scalar mathematical function, i.e: unitless.
With units means garbage-in = garbage-out
Units of what in a unitless CAS ?

jmG

[RichardJ]

The symbolic processor knows nothing about units. It just sees cm and m as undefined variables. If you type m:100*cm before your expression the symbolic evaluation will pick up on that.

Richard

[McHale-disabled]

Thanks to all of you!
I tried Richard's solution and it worked!
I updated the files above.

Regards,
Martin