Evalyating a Polynomial Graph

[awibroe]

Hello,

Firstly, this is a feature of Mathcad I am exploring for the first time.

I am looking at a problem whereby I have a series of coordinates which I have used to plot a graph.

I now need to evaluate the graph in two ways. One I need to find what the largest value on the y value is and then the point at which the curve crosses the x axis (for the second time).

I can do this by eye and say that y is larges at ~0.52 and the curve crosses the x axis at ~84 degrees.

Is there a way to evaluate this mathematically to get a more accurate approximation?

Also can anyone tell me how I can increase the accuracy of the scales i.e. the points on the x axis of interest are currently 81 then 90. How can I show more points i.e. increments of 1 degree on the x axis?

Thanks,

Andy.

[vlehner]

Hi Andy,

Answers see attachement.

Hope it will be helpful.

Best regards, Volker

[awibroe]

Hi There,

I have Mathcad Prime 3 and it will not allow me to open the file because it is made from a later version. Is it possible to save it in a format I can open?

[vlehner]

Ah! I'm working in MCP4. So lets communicate via PDF-File.

[awibroe]

‌yyeah I have an acedemic copy and bought it just before 4 came out so I'm stuck with 3.

[vlehner]

Klick the second number on the x-Achse and change it to e.g 5.

Mathcad takes the steps in5 steps up to 90.

see this:

[awibroe]

I've looked through the PDF as I cant open the Mathcad file. I am clearly not doing something correctly as I get a different value to you?

[awibroe]

Also, are the lines you have on added manually or is this something mathCad can do?

Also, is the value at which the graph crosses the x axis near 85degrees achievable in the same way?

[vlehner]

You can add the Lines This way-It's not automaticly:

click into the diagramm, switch menue to "Diagramme" and choose this: horizontal and vertikal markers

you must change the Values manual.

I took the values from my solution in th solve block (copy and paste it into the diagram-Markers for x and y.

Volker

[awibroe]

‌tthanks!

any idea on why the values I'm generating are not the same as yours? I think I've followed the procedure correctly?

[vlehner · Accepted solution]

change the unit from Thetaxmax to °:

[awibroe]

Legendary!

Thanks for that and it seems the same approach can be taken for the second part of my question which I have done!

[vlehner]

Thank you!