MaplePrimes - answers and comments on Question, How do I apply a range of values to a variable in an equation or function?

How to plot

Carl Love — Sun, 27 Jan 2013 05:07:48 Z

First, get rid of the line k:= 0, 1..npts/2. Do a restart to eliminate the effect of that command. Then, at the end, do

plot(Zuncomp(k), k= 0..npts/2, labels= ["k", "Zuncomp"])

Spotted a typo DC should be 113700m (113.7km

arctica1963 — Mon, 28 Jan 2013 04:04:07 Z

Spotted a typo DC should be 113700m (113.7km) - still does not solve the problem

flexp needs to be a function

Carl Love — Mon, 28 Jan 2013 08:08:52 Z

I found two problems. The first one I don't really understand, but anyway, I needed to retype Zpratt in the plot command. I could tell there was something wrong with it because the "pratt" was not in italics.

The second problem is more mathematical. You need to make flexp a function of k, i.e. you need a "k ->" in front of the expression. Then when you refer to flexp in the two final Z function definitions, make it flexp(k).

As for putting the plots together, the command is plots:-display, not simply display. So,

plots:-display([A,B, etc.]);

Finally, there are linestyles other than dash. They are solid, dot, dash, dashdot, longdash, spacedash, or spacedot.

I added the changes you spotted, but the

arctica1963 — Mon, 28 Jan 2013 12:20:41 Z

I added the changes you spotted, but the last plot is incorrect compared to the SCILAB output, so need to investigate that. Otherwise so far so good it is all getting there. One thing I needed to remember was that restart clears the variables and so they need to be reinitialised.

The plots now all work! Also spotted that

arctica1963 — Tue, 29 Jan 2013 00:05:50 Z

The plots now all work! Also spotted that I needed a different flexp parameter for the Zsubload, so put that in and the plot scale was all sorted. Bit fiddly but got there in the end :) Thanks for the help on this, still pretty new with using Maple so it takes a little getting used to.

The equations relate to different isostatic models of the Earth's lithosphere (the Crust and uppermost mantle) to see how they vary with wavelength and the admittance function (Z(k) )=fft(gravity)/fft(topography). The actual equations simplify to more usable structures.

I am a geologist by training and currently completing a PhD in geodynamics.

The equations are found in the book by Tony Watts - Isostasy and flexure of the lithosphere (2001)

Have some more complex functions to work on in Maple so will give those a try later on. Early days with Maple and I am sure I will have more queries as I learn it more.

Thanks again for the help

Just a quick query. Now that I have the plot

arctica1963 — Tue, 29 Jan 2013 03:21:04 Z

Just a quick query. Now that I have the plot generated with the wavenumber (k) on the x-axis (bottom), is it possible to have a different scale on the top x-axis which is the wavelength? So we would have a linear wavenumber scale on the bottom and the corresponding wavelength on the top:

wavelength = 2*Pi / wavenumber(k)

I can alter the properties of the graph from the menu options, but the secondary axis only applies to Y and not X

Will be interested to know how this would work and if it is easy or tricky to do.

Cheers

FAA_isostatic1e.mw