3D Scatter Plot with Natural Log Element MathCAD 14

[ebrady-2]

In MathCAD 14, I am having trouble making a 3D scatter plot when the matrix-function contains an element that is a natural log function. The same matrix-function plots OK If I substitute and different function for the natural log function. I have included an example file; why does the p.2xyz function plot OK and p.1xyz not plot at all?

[ebrady-2]

correction: "substitute a dirfferent" not "substitute and dirfferent"

[Werner_E]

Erroll Brady wrote:

correction: "substitute a dirfferent" not "substitute and dirfferent"

Even better "substitute a different", I guess.

BTW, as long as nobody has replied to a post of yours, you can still edit it. If its the initial post you find the option to do so in the outer right column, otherwise at the end of the posting.

[ebrady-2]

Yes. I suffer from doofus-finger.

Thanks.

[Werner_E]

Erroll Brady wrote:

Yes. I suffer from doofus-finger.

Thanks.

I can perfectly understand that as I have a similar problem 😉

Hope the answer below helped anyway.

[Werner_E · Accepted solution]

Unlike a 2D-plot a 3D plot will not respect and use your range t. So you used the 3D quickplot and it defaults to a range from -5 to 5. Give it a try, change your t-range and watch your second plot - nothing will happen.

The negative values in the range [-5; 5] throw a complex result, 0 makes the log function fail. Unlike a 2D plot a 3D plot fails if just one result is complex or NaN or the like.

To make your plot work you have to edit the quickplot range accordingly:

It may be more convenient to use the CreateSpace() function at the price of having to get rid of the units (which you should do in a 3D-plot anyway):

[ebrady-2]

Thank you,

That did the trick.

Erroll