Re: ListPlot3D

*To*: mathgroup at smc.vnet.net*Subject*: [mg131203] Re: ListPlot3D*From*: Bill Rowe <readnews at sbcglobal.net>*Date*: Mon, 17 Jun 2013 06:27:11 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-outx@smc.vnet.net*Delivered-to*: mathgroup-newsendx@smc.vnet.net

On 6/16/13 at 5:15 AM, Anthony.J.Mannucci at jpl.nasa.gov (amannucci) wrote: >I could use some help with ListPlot3D. These are examples from the >documentation. My preconceived notion of what this should do is >place a data point at coordinates {x,y,z} and connect a surface >along the z_i. Here is an example from the Mathematica >documentation: >ListPlot3D[{{1, 1, 1, 1}, {1, 2, 1, 2}, {1, 1, 3, 1}, {1, 2, 1, 4}}, >Mesh -> All] >I cannot figure out how to read these data. What are the x,y values? ListPlot3D works in the same manner as ListPlot. When you do ListPlot[{2,4,6,3}] You are supplying a list of y-coordinates with implied x-coordinates running from 1 to 4. So, the first point is plotted at (1,2), the second at (2,4) and so on. Likewise, ListPlot3D takes an array of z-valus with implied values for both the x and y coordinates. The first row has an x coordinate of 1 with y coordinates running from 1 to 4. The next row has an x coordinate of 2 with y coordinates running from 1 to 4 and so on. To see this look at ListPlot3D[{{5, 1, 1, 1}, {1, 2, 1, 2}, {1, 1, 3, 1}, {1, 2, 1, 4}}, Mesh -> All] and ListPlot3D[{{1, 5, 1, 1}, {1, 2, 1, 2}, {1, 1, 3, 1}, {1, 2, 1, 4}}, Mesh -> All] and notice where the peak appears in the resulting plot. >when I feed in the following data set, the graph is completely blank: >{{0., 0., 0.}, {0.1, 0.1, 0.248514}, {0.2, 0.2, 0.329812}, {0.3, 0.3, >0.324989}, {0.4, 0.4, 0.275382}, {0.5, 0.5, 0.207606}, {0.6, 0.6, >0.138975}, {0.7, 0.7, 0.0799098}, {0.8, 0.8, 0.0358315}, {0.9, 0.9, >0.008981}, {1., 1., 0.}} With this data set at every point {x, y, z}, the x and y coordinates are identical. Consequently, it defines a curve in space not a surface. >x and y span 0->1. There are z-values, but nothing is plotted. If I manually change the first three data points to be (mimicing the docs): >{0., 0., 0.}, {1.0, 0.0, 0.248514}, {0., 1., 0.329812} Right, now you have defined a surface since you have altered the x,y coordinates so they are not equal everywhere.