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# Plot several points as coordinates and colouring.

Posted 11 years ago
 Hi,I'm trying to get a second point , which is a coordinate, onto my plot, but I can't seem to find a way to get past the constant erroring. As for coloring the point/points I seem to have the same problem. Plot[y = Sqrt[x], {x, 0, 300}, Epilog -> {PointSize[0.018], Point[{10, 9}]}, PlotStyle -> Brown]The second point is supposed to be (70,9), and I have tried making a Table, ListPlot and such, but so far no result.
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Posted 11 years ago
 Here is something I was working on a while back, it contains most of the ideas you are looking for and some others you may find useful. In:= ContourPlot[{x + 4 x^2 - 8 y + 5 x y + 4 y^2 == 0,    y == 8 x + 27, y == -x - 1, y == -(8/11) x + 25/11, y == 1/8 x ,    y == -(11/8) x + 2, y == -x + 7/13}, {x, -4, 2}, {y, -1, 5},   Epilog -> {Blue, PointSize[Large],     Point[{{-3, 3}, {-2, 1}, {-1, 3}, {0, 0}, {0, 2}, {4/3, 1/       6}, {-(8/9), -(1/9)}, {-(8/19), 49/19}, {-(17/6), 13/       3}, {-(28/9), 19/9}, {-(16/13), 23/       13}, {-(2/39) (24 + 5 Sqrt),        23/13 + 10/Sqrt}, {2/39 (-24 + 5 Sqrt),       23/13 - 10/Sqrt}}], Joined -> True, Mesh -> Full}, GridLines -> {Range[-4, 2], Range[-1, 5]}]
Posted 11 years ago Plot for the last bit of code.  Should have put it in the same post.
Posted 11 years ago
 To make all the points the same color, include a color directive in the list as you did the size directive. coords = Table[{x, 9}, {x, 10, 250, 60}];Plot[y = Sqrt[x], {x, 0, 300},     Epilog -> {Red, PointSize[0.018], Point[ coords ]},     PlotStyle -> Brown]To make the points different colors, it's probably easiest to make the Points in a Table and include the color directive there.  PlotStyle still applies to the curve. The PointSize directive goes in the Eplilog list before the Points. coordsR = Table[{Hue[x/300], Point[{x, 9}]}, {x, 10, 250, 60}];Plot[y = Sqrt[x], {x, 0, 300},    Epilog -> {PointSize[0.018], coordsR},    PlotStyle -> Brown]
Posted 11 years ago
 Oh... Thank you!And as for the colouring then?
Posted 11 years ago
 I am not sure what the problem is. To include more than one point, give a list of the {x,y}  coordinates, like    Point[ { {x1,y1}, {x2,y2}, ..} Plot[y = Sqrt[x], {x, 0, 300},    Epilog -> {PointSize[0.018], Point[{{10, 9}, {70, 9}}]},    PlotStyle -> Brown]To make a list of coordinates with Table, include the expressions for x and y in a list, coords = Table[{x, 9}, {x, 10, 250, 60}];Plot[y = Sqrt[x], {x, 0, 300},  Epilog -> {PointSize[0.018], Point[ coords ]},   PlotStyle -> Brown]