Maxima plot - SMath

#1 Posted: 1/22/2026 10:52:55 AM

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Hi, i would like to add some points to 3D plot. How can I do that?
And can i somehow make the plot smooth without using smaller steps in vectors?

Kompresibilita_3D.sm (56.04 KiB) downloaded 215 time(s).

Thanks for answers,
Tomas

Edited 1/22/2026 10:54:05 AM

#2 Posted: 1/22/2026 2:08:14 PM

Martin Kraska

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You could try to create a mesh of triangles or quadrilateral objects. Then you are free to use a problem-adjusted surface parametrization.

Technische Mechanik mit SMath Studio: https://link.springer.com/book/10.1007/978-3-658-50592-9

#3 Posted: 1/27/2026 9:55:32 PM

Tomas Novotny

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Hi,
thanks for your answer. I have another question. I´m trying to make graph of water density, but the axes are not right, what is wrong?

hustota vody.sm (69 KiB) downloaded 122 time(s).

Thanks,
Tomáš

#4 Posted: 1/28/2026 12:09:04 AM

Martin Kraska

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This is probably due to the "visual" indexing in the matrix.

Rows in a matrix are increasing top-down, whereas values in y are increasing bottom-up.

Technische Mechanik mit SMath Studio: https://link.springer.com/book/10.1007/978-3-658-50592-9

#5 Posted: 1/28/2026 8:23:58 AM

Tomas Novotny

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Thanks you very much! That helped.
But if i want to make axes right i have to switch x and y axes in elevation grid command. I don’t know why.

hustota vody.sm (135.01 KiB) downloaded 127 time(s).

Is there any sheet of something like that, where I can fing all comands for plots? And how can I write them, because commands that I used, I copied from some file I found.

Thanks for answers,
Tomáš

#6 Posted: 1/28/2026 5:30:00 PM

Martin Kraska

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See topic starter https://smath.com/en-US/forum/topic/cnc5Xp/Maxima-Plugin. I added some references there.

Technische Mechanik mit SMath Studio: https://link.springer.com/book/10.1007/978-3-658-50592-9

#7 Posted: 1/28/2026 7:33:40 PM

Tomas Novotny

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That is awesome!

Thanks,
Tomáš

#8 Posted: 2/6/2026 11:03:04 AM

Tomas Novotny

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Hi,
how can I add point B to plot? When I tried I make point or plot, but not both of them.

kriticky_bod.sm (202.22 KiB) downloaded 63 time(s).

Thanks for answers,
Tomas

#9 Posted: 2/6/2026 1:25:26 PM

Martin Kraska

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Seems to be related to the negative temperature range in the elevation_grid command.

Technische Mechanik mit SMath Studio: https://link.springer.com/book/10.1007/978-3-658-50592-9

#10 Posted: 2/10/2026 7:29:28 AM

Tomas Novotny

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Thanks for answer,
I tried to fix it and I ended with this. Still can t plot graph and point together.

kriticky_bod.sm (201.86 KiB) downloaded 50 time(s).

What should I do now?

Tomáš

#11 Posted: 2/10/2026 3:54:04 PM

Martin Kraska

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You still have a negative h value (temperature difference). Reverse this (and also reverse the matrix). Then it should work.

Technische Mechanik mit SMath Studio: https://link.springer.com/book/10.1007/978-3-658-50592-9

#12 Posted: 2/19/2026 8:34:45 AM

Tomas Novotny

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Thank you very much! It works.

Tomáš

#13 Posted: 2/19/2026 10:12:49 AM

Martin Kraska

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Good to see. You also might display the z values in MJ/kg to get nicer tick labels and play around with the view parameters in the settings menu to avoid interference between axis label and tick labels.

Technische Mechanik mit SMath Studio: https://link.springer.com/book/10.1007/978-3-658-50592-9

#14 Posted: 2/19/2026 11:38:12 AM

Tomas Novotny

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Now I would like to add saturation curve. Is it better to go with matrix or function? And how can I do that?

I tried parametric function, but plot did not work.

krit_bod_2.sm (211.84 KiB) downloaded 19 time(s).

Thanks for answers!

Tomáš

Edited 2/19/2026 12:05:07 PM

#15 Posted: 2/19/2026 1:01:39 PM

Martin Kraska

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I guess it is best to use the points object just like for the single point. Set points_joined to true, point_type to something convenient. Using a function will work only if that function is supported by the interface to Maxima, which probably doesn't apply to coolprop functions or interpolated functions.

Technische Mechanik mit SMath Studio: https://link.springer.com/book/10.1007/978-3-658-50592-9

#16 Posted: 2/22/2026 6:05:46 PM

Tomas Novotny

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Hi,
I’m back. I tried to create line of points by maxima handbook. Handbook is really great, but I couldn’t figure it out. What am I doing wrong? Matrix seems right.

And i have another question. When I created plot of enthalpy I just wrote name of the "plot function". But in the manual, there is Draw3D("plot function"). Why is that?

saturation_curve.sm (194.75 KiB) downloaded 9 time(s).

Thanks for your help and patient, I really appriciate it.

Tomáš

#17 Posted: 2/23/2026 10:20:19 AM

Martin Kraska

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Your data matrix isn't in the correct format. It is a one-column matrix of row vectors. Make it a real n x 3 matrix, then try again.

Also, you use different units when filling the data matrix (J/kg) and for the axis limits (kJ/kg).

As to the Draw3D command, see intro text to Chapter 3.

Technische Mechanik mit SMath Studio: https://link.springer.com/book/10.1007/978-3-658-50592-9

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