MaplePrimes - Newest Comments

@acer Concering _a I am missed exact terms....

C_R — Wed, 08 Apr 2026 18:33:27 Z

Concering _a I am missed exact terms. I read somewhere parameter.

Yes I want _a in the outer RootOf (yellow) not beeing used in the inner RootOf (green) in case they are not the same. The _a encircled in red is something I have difficulties to interprete. Why is this ??? named the same as the variable of integration?

What Root is returned? The value of _a

Example

Kitonum — Wed, 08 Apr 2026 16:27:03 Z

A:=<1,2,3; 4,5,6>;
B:=<1,2; 3,4>;
<A|B|A>;

pardon?

acer — Wed, 08 Apr 2026 07:19:49 Z

What do you mean by the "...does the _a belong to the outermost RootOf"?

The _a is not a placeholder for any RootOf. It is not acting like _Z, say.

The _a is a variable-of-integration.

Are you wanting to change the name(s) of the variable of integration, going from inside to out?

Import

acer — Wed, 08 Apr 2026 06:47:01 Z

One difficulty, AFAICS, is that every character in your .txt file is separated by a zero-byte null instance. I got rid of those using a Linux command in a terminal shell.

Your criteria for where your regions began/ended are rather vague and hazy, so I just used small values like 0.1,0.3.

I make a list from the 2nd column, and then search that for the positions where your described changes happen.

Links to file attachments are at the end.

restart;

>	# After removing all zero-byte null instances. # I did that in Linux with: tr -d '\0' < F12_1.txt > foo.txt M := ImportMatrix("foo.txt"):

>	# retain only rows with only numeric and nonnegative entries. newM:=M[[seq(`if`(andmap(type,M[i],And(numeric,nonnegative)),i,NULL),i=1..op([1,1],M))]]:

>	# number of rows and columns op(1,newM);

>	plot(newM[..,[1,2]],size=[700,300]);

>	L2 := convert(newM[..,2],list):

>	p1 := ListTools:-SelectFirst(1,(u->u>0.1),L2,output=indices)[1];

>	p2 := p1 + ListTools:-SelectFirst(1,(u->u<0.1),L2[p1+1..],output=indices)[1];

>	plot(newM[p1..p2,[1,2]], view=[0..newM[p2,1]*1.1, default], size=[700,300]);

>	p3 := p2 + ListTools:-SelectFirst(1,(u->u>0.3),L2[p2+1..],output=indices)[1];

>	p4 := p3 + ListTools:-FindMaximalElement(L2[p3+1..], position)[2];

>	# slope (newM[p4,2] %- newM[p3,2]) %/ (newM[p4,1] %- newM[p3,1]); value(%);

>	plot(newM[..,[1,2]],size=[700,300], axis[1]=[tickmarks=[[newM[p1,1],newM[p2,1],newM[p3,1],newM[p4,1]],rotation=Pi/4]]);

Download FDS_ERT_01ac.mw

foo.txt

Update Chapt GTP

C_R — Wed, 08 Apr 2026 05:24:17 Z

images on surfaces

acer — Wed, 08 Apr 2026 00:48:37 Z

Projection mapping of an image onto a sphere can be done.

For example (since Maple 18), see here. That old Post started out as code to do it through various Array and plotting structure programming techniques. But these days it can be done directly with the command plot3d and its image option.

You don't have to scale down the imported image, but its manual rotation, etc, in the GUI can get sluggish, if the image is large. If you don't want to scale it then you could simply pass that URL string as the value for plot3d's image option.

raw:=ImageTools:-Read("https://www.evl.uic.edu/pape/data/Earth/512/PathfinderMap.jpg"):
img:=ImageTools:-Scale(raw,1..201):

plot3d(1,th=0..2*Pi,p=-Pi..0,image=img,coords=spherical);