plotting - "Not a valid Filling specification" error

I have a function, which plots the given function array f. This is a part of the function:

Plot[-f, {x,0,2}, Filling->{1->{2}}, PlotStyle->Green]

When I specify {x^2, 2x} as the function f, I get the errors "2 must be an integer between 1 and 1. " and "{2} is not a valid Filling specification.". I get this error because I have a minus sign in front of the argument f. If I plot {-x^2,-2x} then everything is fine. So how to multiply everything in f by -1 without getting these errors?

Answer

You need to evaluate the first argument of Plot before sampling the specific datapoints, as the multiplication (the minus sign before the list of functions) does not get thread over the list by default, as Plot has attribute HoldAll. This means that your example Plot is practically called with only one function (which is a List) and therefore the Filling specification does not make sense. Discussed in more detail here.

Plot[Evaluate[-{x^2, 2 x}], {x, 0, 2}, Filling -> {1 -> {2}}, PlotStyle -> Green]

This effectively equals the following (note that the - signs are in front of the individual functions):

Plot[{-x^2, -2 x}, {x, 0, 2}, Filling -> {1 -> {2}}, PlotStyle -> Green]

Both produce the following correct plot:

Mathematica graphics

Comments

plotting - Plot 4D data with color as 4th dimension

I have a list of 4D data (x position, y position, amplitude, wavelength). I want to plot x, y, and amplitude on a 3D plot and have the color of the points correspond to the wavelength. I have seen many examples using functions to define color but my wavelength cannot be expressed by an analytic function. Is there a simple way to do this? Answer Here a another possible way to visualize 4D data: data = Flatten[Table[{x, y, x^2 + y^2, Sin[x - y]}, {x, -Pi, Pi,Pi/10}, {y,-Pi,Pi, Pi/10}], 1]; You can use the function Point along with VertexColors . Now the points are places using the first three elements and the color is determined by the fourth. In this case I used Hue, but you can use whatever you prefer. Graphics3D[ Point[data[[All, 1 ;; 3]], VertexColors -> Hue /@ data[[All, 4]]], Axes -> True, BoxRatios -> {1, 1, 1/GoldenRatio}]

plotting - Filling between two spheres in SphericalPlot3D

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plotting - Mathematica: 3D plot based on combined 2D graphs

I have several sigmoidal fits to 3 different datasets, with mean fit predictions plus the 95% confidence limits (not symmetrical around the mean) and the actual data. I would now like to show these different 2D plots projected in 3D as in but then using proper perspective. In the link here they give some solutions to combine the plots using isometric perspective, but I would like to use proper 3 point perspective. Any thoughts? Also any way to show the mean points per time point for each series plus or minus the standard error on the mean would be cool too, either using points+vertical bars, or using spheres plus tubes. Below are some test data and the fit function I am using. Note that I am working on a logit(proportion) scale and that the final vertical scale is Log10(percentage). (* some test data *) data = Table[Null, {i, 4}]; data[[1]] = {{1, -5.8}, {2, -5.4}, {3, -0.8}, {4, -0.2}, {5, 4.6}, {1, -6.4}, {2, -5.6}, {3, -0.7}, {4, 0.04}, {5, 1.0}, {1, -6.8}, {2, -4.7}, {3, -1....

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