Carl Love

## 19074 Reputation

7 years, 349 days
Mt Laurel, New Jersey, United States
My name was formerly Carl Devore.

## No easy way...

I don't think that there is any easy way to add a second horizontal axis. You'd just have to fake it by plotting line segments and using textplot for the tickmark labels. However, note that the tickmarks and the tickmark labels on any actual axis can be changed relatively easily. What is printed for the tickmark labels does not need to correspond numerically to what is in the plot. Indeed, the tickmark labels don't even have to be numbers. So, you could modify the one existing horizontal axis to reflect whatever scale you want.

If you wish to persue this, please post the question in a fresh thread.

## No easy way...

I don't think that there is any easy way to add a second horizontal axis. You'd just have to fake it by plotting line segments and using textplot for the tickmark labels. However, note that the tickmarks and the tickmark labels on any actual axis can be changed relatively easily. What is printed for the tickmark labels does not need to correspond numerically to what is in the plot. Indeed, the tickmark labels don't even have to be numbers. So, you could modify the one existing horizontal axis to reflect whatever scale you want.

If you wish to persue this, please post the question in a fresh thread.

## Can't say exactly...

@Markiyan Hirnyk I spent a few hours thinking about the problem while washing dishes and doing laundry. Mostly I thought about how I could apply the LogicProblem package to it. I am very familiar with that package, because I wrote it. But I have not used it in eight years, so the details are not sharp in my mind. Eventually I decided that this problem was not suited for that package.

I view this problem immediately as a combinatorics problem---more specialized than simply logic. Combinatorics is very close to graph theory. Also, the symmetry of 12 and 5 together is very appealing to me (think of dodecahedra). Once I considered using graph theory, the way to do the problem was obvious to me.

How did you do the problem? Finding 3-cliques in this problem is easy, even just by hand and without using a graph. The hard thing is proving that there are no 4-cliques.

## Can't say exactly...

@Markiyan Hirnyk I spent a few hours thinking about the problem while washing dishes and doing laundry. Mostly I thought about how I could apply the LogicProblem package to it. I am very familiar with that package, because I wrote it. But I have not used it in eight years, so the details are not sharp in my mind. Eventually I decided that this problem was not suited for that package.

I view this problem immediately as a combinatorics problem---more specialized than simply logic. Combinatorics is very close to graph theory. Also, the symmetry of 12 and 5 together is very appealing to me (think of dodecahedra). Once I considered using graph theory, the way to do the problem was obvious to me.

How did you do the problem? Finding 3-cliques in this problem is easy, even just by hand and without using a graph. The hard thing is proving that there are no 4-cliques.

## Extra rho factor in Zsubload...

@arctica1963 Your expression for Zsubload has an extra factor of "rho". Take out the (rhoload - rhowater) in front. Note that each term of the complicated coefficient at the end already contains a "rho" factor.

Just a guess, but do these formulae have to do with airplane radio interference caused by power transmission cables?

## Extra rho factor in Zsubload...

@arctica1963 Your expression for Zsubload has an extra factor of "rho". Take out the (rhoload - rhowater) in front. Note that each term of the complicated coefficient at the end already contains a "rho" factor.

Just a guess, but do these formulae have to do with airplane radio interference caused by power transmission cables?

## Is the x^0 term zero also...

Is the x^0 term (the "constant" term) of the series supposed to set to zero also?

I see both uppercase Omega and lowercase omega in your formula, both always squared. Is that a typo, or do they represent different things?

## That's not plain text...

That's an image, not plain text. Either upload a worksheet, or plain text.

## We can get a fairly close replica...

@arctica1963

We can get a fairly close replica of the SCILAB plot like this: First, define a scaling function:

kscale:= k-> k/XKINT*0.001;

Then use this plot command:

plot(
Zuncomp@kscale, 0..0.8
,labels= ["Wavenumber k (1/km)", "Free-air admittance"]
, labeldirections = [horizontal, vertical]
,color = green, linestyle = dash
,view = [0..1, -30..80]
,axes = boxed, gridlines, legend = ["Uncompensated"], legendstyle = [location = top]
);

Note in particular that the first argument is Zuncomp@kscale. The `@` represents functional composition. Also note that the second argument, 0..0.8, is simply a range rather than variable= range. That is necessary because the first argument is now a function rather than an expression. In other words, it doesn't depend on k anymore. I got the 0.8 from the SCILAB plot. If for didactic reasons you need the upper limit expressed in terms of npts, then we can work on that. Let me know how it goes.

## We can get a fairly close replica...

@arctica1963

We can get a fairly close replica of the SCILAB plot like this: First, define a scaling function:

kscale:= k-> k/XKINT*0.001;

Then use this plot command:

plot(
Zuncomp@kscale, 0..0.8
,labels= ["Wavenumber k (1/km)", "Free-air admittance"]
, labeldirections = [horizontal, vertical]
,color = green, linestyle = dash
,view = [0..1, -30..80]
,axes = boxed, gridlines, legend = ["Uncompensated"], legendstyle = [location = top]
);

Note in particular that the first argument is Zuncomp@kscale. The `@` represents functional composition. Also note that the second argument, 0..0.8, is simply a range rather than variable= range. That is necessary because the first argument is now a function rather than an expression. In other words, it doesn't depend on k anymore. I got the 0.8 from the SCILAB plot. If for didactic reasons you need the upper limit expressed in terms of npts, then we can work on that. Let me know how it goes.

## Rectangular...

@emma hassan I used your file and I was able to do the ImportData(). After selecting float[8](64-bit), on the next screen, Skip rows and Skip columns should both be 0. Then press Next. On the next screen, select Rectangular, then press Next. On the next screen, put in M for the variable name, then press Done. You'll be returned to your Maple worksheet, and you'll be able to issue the surfdata command.

## Rectangular...

@emma hassan I used your file and I was able to do the ImportData(). After selecting float[8](64-bit), on the next screen, Skip rows and Skip columns should both be 0. Then press Next. On the next screen, select Rectangular, then press Next. On the next screen, put in M for the variable name, then press Done. You'll be returned to your Maple worksheet, and you'll be able to issue the surfdata command.

## To plot it, parameters need values...

Now we have three parameters: y, X, and T. Maple can give a parametric numeric solution, but in order to plot anything we'll need specific values for the parameters.

Also, you've used both x and t to represent the independent variable. That makes no difference to Maple, but it is sloppiness that makes your material more confusing for a human to read. Finally, y, X, and T are unusual letters to use to represent parameters. Again, it makes no difference to Maple, but without some context for why those letters are used, it causes confusion for the reader.

## To plot it, parameters need values...

Now we have three parameters: y, X, and T. Maple can give a parametric numeric solution, but in order to plot anything we'll need specific values for the parameters.

Also, you've used both x and t to represent the independent variable. That makes no difference to Maple, but it is sloppiness that makes your material more confusing for a human to read. Finally, y, X, and T are unusual letters to use to represent parameters. Again, it makes no difference to Maple, but without some context for why those letters are used, it causes confusion for the reader.

## Sorry that I wasn't more specific about ...

@arctica1963 I'm sorry that I wasn't more specific about restart. Put the restart at the beginning of your document. It's a good idea to start all computations with restart, which erases all user-defined values from memory. It's like the "all clear" button on a pocket calculator. See ?restart. Where you have the restart now is erasing everything you just defined right before you try to plot it.

Let me know how it goes. I got the plot that you expect, except that the horizontal axis is from 0 to 512. Get the plot first, then we can rescale the axis.

 First 531 532 533 534 535 536 537 Last Page 533 of 547
﻿