Get Help

Turn on suggestions

Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.

Showing results for

- Community
- :
- PTC Mathcad
- :
- PTC Mathcad
- :
- Parabola-Mirror - an error?

Options

- Subscribe to RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic for Current User
- Bookmark
- Subscribe
- Printer Friendly Page

Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.

Showing results for

Highlighted

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

12-28-2015
03:09 AM

12-28-2015
03:09 AM

Where is an error? Help please!

(One more same problem What is not correct in this optic problem?)

I know other simple solution this optic task (see please bellow), but I would like use this:

Simple solution - symbolic (by WolframAlpha.com site) and numeric (with nanotechnology help):

Solved! Go to Solution.

1 ACCEPTED SOLUTION

Accepted Solutions

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

12-28-2015
12:01 PM

25 REPLIES 25

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

12-28-2015
06:41 AM

12-28-2015
06:41 AM

Re: Parabola-Mirror - an error?

What do you mean by this equation

and where does it stem from?

And why do you think that the argument of y´ should be a length (x(alpha)) while the argument of y is an angle?

If you write y´ here it has in any case to be the derivative with respect to alpha.

WE

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

12-28-2015
09:33 AM

12-28-2015
09:33 AM

Re: Parabola-Mirror - an error?

I think you need to do it like the following Valery:

Note that the gradient is infinite at x = -F, which leads to difficulties for the integration routine. Hence the definition of the gradient function above.

Alan

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

12-28-2015
09:52 AM

12-28-2015
09:52 AM

Re: Parabola-Mirror - an error?

Thanks, Alan and Werner.

The Prime 3 sheet in attach is without an error but has a false tan not sin in the last equation.

I feel the error but...

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

12-28-2015
09:53 AM

12-28-2015
09:53 AM

Re: Parabola-Mirror - an error?

Yes, Werner - not alpha but x - see please bellow

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

12-28-2015
10:50 AM

12-28-2015
10:50 AM

Re: Parabola-Mirror - an error?

You may be able to keep alpha as the independend variable, but you can't use y'(x(apha)).

What you mean is

which Mathcad can't unserstand and you will have to replace it by

If you do so, other errors occur, though.

But I see you already rewrote your equations to accommodate for x as the independent variable, anyway.

WE

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

12-28-2015
10:57 AM

12-28-2015
10:57 AM

Re: Parabola-Mirror - an error?

Thanks, but

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

12-28-2015
11:00 AM

12-28-2015
11:00 AM

Re: Parabola-Mirror - an error?

Yes, I told you that you will run into other errors so it seems it was only the first mistrake in a row of others.

WE

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

12-28-2015
11:17 AM

12-28-2015
11:17 AM

Re: Parabola-Mirror - an error?

From unnecessary ballast freed system but I don't understand what the error message would like to tell us!?

Looks like Mathcad does not like both derivaties to be in one equation.

- Mark as New
- Bookmark
- Subscribe
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

12-28-2015
11:56 AM

12-28-2015
11:56 AM

Re: Parabola-Mirror - an error?

Here we go.

It was necessary to introduce a dummy function and to redefine tan(). Not convincing, but at least it works.

Werner

Top Tags