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I would like to create a plot in Mathematica similar to

example plot

for the equation $\frac{d P}{dt}=P(0.6-0.003P).$

My attempt so far is

StreamPlot[{1, P (0.6 - 0.003 P)}, {t, 0, 30}, {P, 0, 220}, 
 PlotRangePadding -> Automatic, StreamPoints -> {Automatic, 0.1}, 
 StreamScale -> None, StreamStyle -> {Thick, Dashed}, 
 ImageSize -> Medium, PlotRange -> {{0, 30}, {0, 220}}, Axes -> True, 
 AxesLabel -> {"t", "P(t)"}]

best so far

My questions are

  • Why don't the Axes labels appear on the image?
  • How can I increase the density of the stream points?
  • Can I increase the thickness of the lines?
  • How can I change the colour of the lines to black?
  • Some stream points appear and disappear how can I get rid of these odd looking points?
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  • 1
    $\begingroup$ Use StreamStyle -> {Thickness[0.01], Black, Dashed}; and FrameLabel instead of AxesLabel. $\endgroup$ – corey979 Jan 9 '18 at 19:04
  • $\begingroup$ Do you know how I can increase the density of stream points? $\endgroup$ – AzJ Jan 9 '18 at 19:24
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Given your example graphic, I think you want VectorPlot rather than StreamPlot. Use VectorStyle -> Arrowheads[0] to eliminate the arrowheads, if that's what you want.

VectorPlot[{1, P (0.6 - 0.003 P)}, {t, 0, 30}, {P, 0, 220}, 
     PlotRange -> {{0, 30}, {0, 220}}, Axes -> True, 
     FrameLabel -> {"t", "P(t)"}, 
     VectorStyle -> {Thick, Black, Arrowheads[0]}]

enter image description here

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