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Anonymous
January 3, 2010
Question

Degree-Sign in symbolic calcs

  • January 3, 2010
  • 8 replies
  • 8120 views
I just ran into a (to me) somewhat inconsistent behavior of Mathcad using the °-sign.
Goal was the solution of a goniometric equation in a given interval and in degree, not radiant.

Details in the enclosed Mathcad-File, which was produced with V14-M030 and saved in MC11-Format.

Some questions aroused:

1) Is it possible to tell Mathcad to make its calculations (arc-functions, solve,...) in degree rather than in radiant?

2) Why is ° (as an abbravation for pi/180) not known in symbolic calculations. Is there a reason for that?

3) Just being curious: Why is ° know to symbolic calcs if you tell MC its a real number (see file)

4) Is it possible to produce the output of a symbolic calc in degree without using numeric evaluation?

5) Is there a way to have the output display in the form "(-60°, 60°, 300°)" rather than "(-60 60 300)°" ?

Thanks for any help!

RMix

8 replies

TomGutman1-Visitor
1-Visitor
January 3, 2010
A general feature of Mathcad -- units are known only to the numeric processor. The symbolic processor does not know about units, and unit names are merely undefined variables to it. You can add your own definitions for units, and such definitions will be used by the symbolic processor.
__________________
� � � � Tom Gutman
Anonymous
January 3, 2010

Thanks for the reply

>A general feature of Mathcad
I wouldn't call it a "feature" or is there a specific reason for this behaviour other than the symbolic processor not being fully integrated?


>variables to it. You can add
>your own definitions for
>units, and such definitions
>will be used by the symbolic
>processor.
Yes, thats exactly what i did at last.

Still wonder about my question 3 (2nd attempt in the file). Would have expected MC to still moan abou not knowing °.

Kind regards

RMix



>__________________
> Tom Gutman


TomGutman1-Visitor
1-Visitor
January 3, 2010
No idea what the symbolic processor did for that second case. Something is clearly wrong, as it did a float evaluation even though nothing in the statement of the problem called for float. As to what value it assumed for °, I haven't a clue.
__________________
� � � � Tom Gutman
ptc-13682881-Visitor
1-Visitor
January 4, 2010
You have too many questions outside of normal mathematical practice.

"4) Is it possible to produce the output of a symbolic calc in degree without using numeric evaluation ?"

Trig functions are numerically approximated in radians, convert the symbolic after. Quite an impressive number of symbolic trig will be symbolically evaluated in fractional pi ... try for instance "roots of unity".

jmG
ValeryOchkov24-Ruby IV
24-Ruby IV
January 4, 2010
We can use not only radians and degrees but grads too!
See please:
http://en.wikipedia.org/wiki/Grad_(angle)
Val
http://twt.mpei.ac.ru/ochkov/v_ochkov.htm
ptc-13682881-Visitor
1-Visitor
January 10, 2010
On 1/3/2010 1:48:57 PM, rmix22 wrote:
>I just ran into a (to me)
>somewhat inconsistent behavior
>of Mathcad using the
>�-sign.
>Goal was the solution of a
>goniometric equation in a
>given interval and in degree,
>not radiant.
>
>Details in the enclosed
>Mathcad-File, which was
>produced with V14-M030 and
>saved in MC11-Format.
>
>Some questions aroused:
>
>1) Is it possible to tell
>Mathcad to make its
>calculations (arc-functions,
>solve,...) in degree rather
>than in radiant?
>
>2) Why is � (as an
>abbravation for pi/180) not
>known in symbolic
>calculations. Is there a
>reason for that?
>
>3) Just being curious: Why is
>� know to symbolic calcs
>if you tell MC its a real
>number (see file)
>
>4) Is it possible to produce
>the output of a symbolic calc
>in degree without using
>numeric evaluation?
>
>5) Is there a way to have the
>output display in the form
>"(-60�, 60�,
>300�)" rather than "(-60
>60 300)�" ?
>
>Thanks for any help!
>
>RMix
> ___________________________

You have too many questions that have no mathematical justifications.



jmG



Anonymous
January 10, 2010
>You have too many questions that have no
>mathematical justifications.

That's why it is posted in "Mathcad USAGE Chat"

Thanks for your suggestion "convert(L,degrees)->" but unfortunately it didn't work for me. convert seems to be unknown (and "degrees" seems to have be "deg"). I tried by switching my MC14 to English and have searched the User-Guides of Version 14 and the one of Version 11 (the last one which deserves that name) for a function convert with no success!!??

Regards
RMix
RichardJ19-Tanzanite
19-Tanzanite
January 10, 2010
On 1/10/2010 10:42:07 AM, rmix22 wrote:
>>You have too many questions that have no
>>mathematical justifications.
>
>That's why it is posted in
>"Mathcad USAGE Chat"
>
>Thanks for your suggestion
>"convert(L,degrees)->" but
>unfortunately it didn't work
>for me. convert seems to be
>unknown

It's a Maple function that could be accessed (although it's not documented or supported) in version 11.

Richard
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