bugs - Return value of Import "MX" when file was saved with newer version

I just detected that Mathematica 10.4.1 on Windows will just quietly return Null when I try to Import an .mx file I exported with version 11.1.1. I understand and know that .mx files that were generated with newer versions will generally not load with older versions. Up to now I thought (and I believe I have seen that for older verions) it would give some message and return $Failed, but obviously this is not the case here. As often, the documentation page for the MX format is not giving detailed information about that specific case.

My question is whether that is the expected behavior and whether there is some documentation about that or that would be something to report to WRI...

Answer

This is indeed a bug. A careless tweak was made to the format, so that MX files created by Version 11.1 or newer aren't even recognized as MX files by pre-11.1.0 versions. So Get is succeeding, reading the binary file as text and returning Null because it encounters a zero byte, interpreted as end of file, early on. If for some reason it is important to you that old versions properly recognize and reject newer MX files, you can use the program below after you DumpSave to tweak the MX file. This version will be loaded by V11.1+, and properly rejected as too new by older versions.

On the plus side, one thing we did in the forth coming 11.2 is improve cross-version compatibility of MX files. So, unless a new feature forces an incompatible change in the format, 11.2 will be able to read MX files from later versions. (Obviously, new features won't work in an older kernel).

newHeader = {40, 42, 84, 104, 105, 115, 32, 105, 115, 32, 97, 32, 77, 
   97, 116, 104, 101, 109, 97, 116, 105, 99, 97, 32, 98, 105, 110, 97,
    114, 121, 32, 100, 117, 109, 112, 32, 102, 105, 108, 101, 46, 32, 
   73, 116, 32, 99, 97, 110, 32, 98, 101, 32, 108, 111, 97, 100, 101, 

   100, 32, 119, 105, 116, 104, 32, 71, 101, 116, 46, 42, 41};

newFooter = {40, 42, 69, 110, 100, 32, 111, 102, 32, 77, 97, 116, 104,
    101, 109, 97, 116, 105, 99, 97, 32, 98, 105, 110, 97, 114, 121, 
   32, 100, 117, 109, 112, 32, 102, 105, 108, 101, 42, 41, 0};

fixUp111PlusMX[file_] := With[{bytes = BinaryReadList[file], path = AbsoluteFileName[file]},
   BinaryWrite[path, 
   Join[newHeader, Take[bytes, {79, -49}], newFooter]];
   Close[path]

]

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

Manipulate[ SphericalPlot3D[{1, 2 - n}, {θ, 0, Pi}, {ϕ, 0, 1.5 Pi}, Mesh -> None, PlotPoints -> 15, PlotRange -> {-2.2, 2.2}], {n, 0, 1}] I cant' seem to be able to make a filling between two spheres. I've already tried the obvious Filling -> {1 -> {2}} but Mathematica doesn't seem to like that option. Is there any easy way around this or ... Answer There is no built-in filling in SphericalPlot3D . One option is to use ParametricPlot3D to draw the surfaces between the two shells: Manipulate[ Show[SphericalPlot3D[{1, 2 - n}, {θ, 0, Pi}, {ϕ, 0, 1.5 Pi}, PlotPoints -> 15, PlotRange -> {-2.2, 2.2}], ParametricPlot3D[{ r {Sin[t] Cos[1.5 Pi], Sin[t] Sin[1.5 Pi], Cos[t]}, r {Sin[t] Cos[0 Pi], Sin[t] Sin[0 Pi], Cos[t]}}, {r, 1, 2 - n}, {t, 0, Pi}, PlotStyle -> Yellow, Mesh -> {2, 15}]], {n, 0, 1}]

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....

Blog

Search This Blog