Turn on suggestions

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

Showing results for

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

Showing results for

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

Jul 11, 2012
03:59 PM

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator

Jul 11, 2012
03:59 PM

Getting coefficients of a quadratic equation based on three points

Greetings, can someone provide a hint?

Solved! Go to Solution.

1 ACCEPTED SOLUTION

Accepted Solutions

Jul 11, 2012
04:22 PM

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator

Jul 11, 2012
04:22 PM

8 REPLIES 8

Jul 11, 2012
04:22 PM

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator

Jul 11, 2012
04:22 PM

Provide some guess values for a, b and c.

Stuart

Jul 11, 2012
04:34 PM

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator

Jul 11, 2012
04:34 PM

Thanks Stuart, that looks like it worked.

But then the question follows: why does MathCad expect you to guess values for variables that we trying to solve for? Is that just for the sake of declaration? If that is the case, then it seems awkward, especially, since these values are arbitrary.

Jul 11, 2012
04:55 PM

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator

Jul 11, 2012
04:55 PM

David Aranovsky wrote:

Thanks Stuart, that looks like it worked.

Good. I checked it in Prime 1 after I posted and it worked as well.

But then the question follows: why does MathCad expect you to guess values for variables that we trying to solve for? Is that just for the sake of declaration? If that is the case, then it seems awkward, especially, since these values are arbitrary.

As Fred says, the numerical solvers generally require a starting point (guess values) - the solvers are fairly general and a number of problems have solutions that are dependent on the initial values.

Local minima and maxima are a good example - starting on side of the 'hill' or the other may take you to completely different minima. I posted a worksheet on the Hooke-Jeeves search algorithm here: http://communities.ptc.com/message/185455#185455 . It contains an example near the bottom of what happens when you specify different initial values.

Stuart

Jul 11, 2012
04:35 PM

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator

Jul 11, 2012
04:35 PM

Generally Mathcad wants a starting guess at the answer so it can launch its' numeric solver. You put x and y in for guess values, try assigning guesses for a, b, and c.

Attached is your problem solved in 14/15, I don't know if it will convert to Prime.

Jul 11, 2012
04:41 PM

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator

Jul 11, 2012
04:41 PM

Thanks Fred!

Jul 12, 2012
08:37 AM

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator

Jul 12, 2012
08:37 AM

This is actually a set of *linear* equations in the unknowns, so here are a couple of ways of solving them without the need for initial guesses:

Alan

Jul 26, 2012
01:46 PM

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator

Jul 26, 2012
01:46 PM

Thanks Alan!

Jul 31, 2012
01:22 AM

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Notify Moderator