MaplePrimes - Maple 2019 Posts and Questions

How to mark intersection points

Andiguys — Thu, 22 Jan 2026 12:28:23 Z

Suppose I am plotting a 2D plot and want to highlight the point where two lines intersect. I would like to display this intersection point inside the plot in black font, mark it with an arrow or some visual highlight, and clearly label it. How can I do this?

Additionally, instead of using different colours (blue, green, red) for the lines, I want to distinguish them using different line styles such as solid, dotted, and long-dashed lines. How can I make these changes?

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Error, (in plots:-pointplot) points cannot be converted to floating-point values

Download Manf_profit__t_graph_changes_needed.mw

Multiple plot overlay

Andiguys — Wed, 19 Nov 2025 16:21:00 Z

Syntax for merging and overlaying all three graphs on a single plot.
Include three sets of iso-profit lines on the same axes:
– Case 1: thin solid lines
– case 2: brown dashed lines
– Case 3: grey semi-dashed lines
Also add vector arrows to show the direction of maximum profit increase.
Combined plot = Plot 1 + Plot 2 + Plot 3
Attaching sheet:
case_1.mw case_2.mw Case_3.mw

sample graph:

How to scale plots, to distinguish multiple curves?

Andiguys — Sat, 15 Nov 2025 04:59:43 Z

In the current graph, the three curves appear close together and are hard to distinguish because of a scaling issue. How can we adjust the scale so that each line is clearly visible and separate?

Download Q_SEPERATE.mw

syntax error using union

Andiguys — Wed, 12 Nov 2025 12:07:09 Z

I'm getting an error while executing the for loop after adding a constraint. Could you please help me identify and fix the syntax issue?

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Error, invalid input: `union` received -.3359880537*w <= Pn-.8264559482, which is not valid for its 1st argument

>	R := Array(ArrayTools:-Reshape(M,[3,4,3]),datatype=float[8]):

>	func := Interpolation:-SplineInterpolation([[0.04, 0.08, 0.12],[0.03, 0.05, 0.07, 0.09]],R[..,..,3]):

>	conts := [seq(min(R[..,..,3])..max(R[..,..,3]),(max(R[..,..,3])-min(R[..,..,3]))/8)];

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ContoursWithLabels:= proc(

Download Q_Constraint_error.mw

2D plot of multiple inequalities or maximum

Andiguys — Tue, 11 Nov 2025 07:07:39 Z

I currently have a 3D plot where the axes are Pn, w, and the objective value (TM1, TM2, TM3 are all positive). I want to convert this into a 2D regional plot with Pn on the x-axis and w on the y-axis. How do I write the syntax for generating such a 2D region plot?

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Download Plot_3D_to_2D.mw

Multiple curves in a dual-axis plot

Andiguys — Sun, 09 Nov 2025 16:33:49 Z

I would like to combine all the plots into a single figure. The curves S1, S2, and S3 represent the manufacturer’s profit as Ce varies, and S12, S22, and S33 represent the retailer’s profit for the same changes in Ce. I want all of these displayed together in one plot using a dual y-axis: one axis for the manufacturer’s profit and the other for the retailer’s profit, with Ce on the x-axis. How to create such a dual-axis plot with appropriate scaling so that the differences between the curves are also clearly visible.

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Download All_plots_Combined.mw