While writing my previous post I struggled to find some way of describing that phrase, but could not readily find some. But I believe, at least I use it that way, that it can be used when feeling baffled as to how something has happened or has been achieved. Maybe some natively speaking users can help us foreigners out here.

Being a physicist myself, I know what you are talking about. I asked, I guess, because I thought that maybe you or someone else could justify the steps you take.

Being a physicist myself, I know what you are talking about. I asked, I guess, because I thought that maybe you or someone else could justify the steps you take.

I am impressed. I had no idea how to proceed. However, isn't there some general issues concerning the permissibility of regularization?

I am impressed. I had no idea how to proceed. However, isn't there some general issues concerning the permissibility of regularization?

I did not know about Rule, because I have never really used the Student package. Maybe I should study the package in some detail. Anyway, I could not resist generalizing your idea to an n-ary product version:

with(Student[Calculus1]):
simplify((Rule[`*`]@@nops(expr))(Diff(expr,t)));

I did not know about Rule, because I have never really used the Student package. Maybe I should study the package in some detail. Anyway, I could not resist generalizing your idea to an n-ary product version:

with(Student[Calculus1]):
simplify((Rule[`*`]@@nops(expr))(Diff(expr,t)));

I think I have heard the expression once somewhere, maybe on television. I do not think it readily figures in some dictionary (by the way, nice memory of yours, remembering that I use dictionaries). But I can find "how on Earth" in my dictionary. If I am unsure about the spelling or use of some word or phrase I may also Google it. Try to Google the exact phrase "on gods green earth".

Concerning the maple-tag: I did not even notice the missing comma, sleepy me! Yesterday evening after having shut down my computer I suddenly realized that your approach ought to produce several images, something I did not think about previously, sleepy me, again. And sure enough, your approach does produce several images, having just checked that. That can hardly be the way that MapleSoft had envisioned us using the maple-tag, or what (asking MapleSoft, not you)?

I have not thought very hard about these issue, and so have not considered a wiki-setup in which the users collaborate to improve the content. However, I think that that would require more intense monitoring/moderation of this site from MapleSoft, and that I think will probably not happen due to considerations of manpower and money.

I agree with you, of course, that it would be a nice thing if some 'topics-entangled' threads, containing different topics, could somehow be un-entangled, i.e., placed in different separate threads. That however would require some serious considerations; for instance, keeping links throughout the site consistent.

Thanks for that ingenious way of making a (seemingly) correctly looking image. How on God's green Earth did you arrive at that expression? By divine intervention, or by brute force trial and error?

However, and sorry for that, it does not satisfy me, because such efforts should of course not be needed. Instead MapleSoft need to do something seriously about this malfunctioning tag.

PS: Congratulations on your golden leaf.

So right, so right. Nothing new under the sun, where almost everything seems to be about money.

I agree with you, of course, that it would be very nice if one were allowed to correct typos in ones own post after someone else has replied to it.

But the problem is, I guess, that post-editing would make possible (seriously) inconsistent threads, in which subsequent replies would no longer correspond to the post they are replys to. Of course, such situations would only arise in the case of irresponsible behaviour, so maybe the problem is more academic than real.

Anyway, here is a compromise: If I see an error which I guess the poster would like to correct I usually write a private message making the poster aware of that error, before possibly posting a reply (on some different matters).

The two-argument function arctan is defined as follows: For real arguments x and y, arctan(y,x) is the unique angle v obeying -Pi < v <= +Pi and (cos(v),sin(v)) = (x,y).

The two-argument function arctan is defined as follows: For real arguments x and y, arctan(y,x) is the unique angle v obeying -Pi < v <= +Pi and (cos(v),sin(v)) = (x,y).

Oh boy, all those plot options :-).

I guess that it boils down to too little plot experience on my behalf.