@Rouben Rostamian  

@Carl Love 

@Carl Love and to dharr,

Apparently Maple Primes only allows one reply if I my first view of answers includes two of them.

To dharr: Your answer gives me the incentive to begin learning GraphTheory about which I currently know nothing. I am grateful for this.

To Carl Love: Over the years, among all the experts, it seems to me that your answers show the deepest knowledge of Maple's capabilities. I will strive to understand and benefit from this one. I regret I could not also select your answer at the best one.

@acer Both of your methods are enlightening for me. I will study them further. Thank you for this.

@acer I ran your file_search code against my all purpose folder containing 1017 files, most of which are Maple worksheets. In about 10 minutes it found 28 worksheets containing the phrase "events" and listed their names.

It also emitted about 30 warning messages reading:

"Warning, if d is meant to be the differential symbol (and not just a variable d), use command completion or palettes to enter this expression"

Your code did exactly what I wanted!

Unfortunately, at this time I can't select yours as the best reply.

@acer I hope the other suggesters reply to your latest comment.

@acer At the moment I am busy with another project, so it will be some time before I can try your suggestion. I confirm that am needing a search of 2D input.

On first impression, among the other replies received, I like yours best because it is all within Maple and because you have taken the trouble to originate it.

@gkokovidis Thank you for your suggestion. Now that I have received a number of suggestions, it may take some time for me to try this and I'll report back to you when I do

@rlopez Thank you for your suggestion. It may take some time for me to try this and I'll report back to you when I do.

@acer Thanks for the suggestion.

I'll try it, but to process more than one hundred worksheets this way is intimidating.
A similar approach could be to export each worksheet to Rich Text format, which should  be text searchable.

From your and Carl Love's replies it seems there may be no way to easily search a large number of worksheets.

@Carl Love Unless I've missed one of its capabilities Windows File Explorer will only find words in folder and file names and within text files but not in Maple worksheets.

@acer Thank you for showing me that the problem was one of the difference in precision of the numbers between the two BinarySearch commands. When I use numbers of the same precision the command produces the correct result.

The procedure works well for the few combinations of p,q I tried except the fsolve command produces an error for p,q = 2,3 (Coxeters loxodromic sequence of tangent circles).

A change of plottools:-circle to plottools:-disk displays neither circles nor disks.

@dharr In the next while I will work on understanding the logic of your answer and ask you to clarify anything that puzzles me.

You have given me much to enjoy and probably some new insights to geometry. Thank you!

@dharr I thank you for your reply, however Maple apparently cannot convert even the first few lines of the Mathematica code in the website to which you provided the link.

I am completely unfamiliar with this conversion so it is likely that I am doing it incorrectly using the command MmaToMaple.

Website https://en.wikipedia.org/wiki/Coxeter%27s_loxodromic_sequence_of_tangent_circles contains some specifications for the Coxeter version of the Doyle spiral but nothing describing the logarithmic spirals on which the tangent circles have their centrers.