@Kanellopoulos  The procedure with 2 arguments:

L[1]:=[x1,x2,x3,x4]:
L[2]:=[y1,y2,y3,y4]:

K:=(j::posint, i::integer) -> `if`(irem(i,4)<>0, L[j][irem(i,4)], L[j][4]):

Examples:

K(1,4), K(2,5), K(2,0);

                 x4, y1, y4

Addition: If you want to make this working also for negative  i , replace  irem(i,4)  by  i mod 4

@erik10

PlotFootball := proc(L::list)

local FootballFaces;

uses geom3d, plottools, plots;

  TruncatedIcosahedron(football, point(C, 0, 0, 0), 1);

  FootballFaces := seq(polygon(faces(football)[i], color = `if`(nops(faces(football)[i])=5,L[1],L[2]), linestyle=solid, tickness=3), i = 1 .. 32);

display(FootballFaces, axes = none);

end proc: 

Example:

PlotFootball([red,yellow]);

Maple plots  graphs of expressions (rather than functions) in their domains. The domain of expression - it is the set of all the values of a variable in which the value of the expression is a real number. When operations on the expressions their domains can be changed.

At a strict definition of the function  its domain should be included in the definition. Maple is not obliged to do this for you (it just does not know this). So the workaround for your plotting is

plot([sqrt(x+2*sqrt(x-1))+sqrt(x-2*sqrt(x-1)), sqrt(x-2*sqrt(x-1)), sqrt(x+2*sqrt(x-1))], x = 1 .. 5, color=[red,blue,green], thickness=2,numpoints=5000, scaling=constrained, view=[-0.5..5.5, -0.5..4.5]);

@maple2015  Because Maple simplifies  (sqrt(x-1)+1) + (1-sqrt(x-1)) = 2  and forgets about the domain x>=1 . Of course it was a mistake Maple.

Addition: The similar example

is(x/x=1);

    true

Maple automatically simplifies  x/x  into  1  and  forgets that  x  should be not 0

@Markiyan Hirnyk   Your recent comments like trolling, so I stop this discussion.

@Markiyan Hirnyk   Because  x= 0.02612014634  does not belong to  0.01338216460 < x and x <= 0.02612014630

@Markiyan Hirnyk  For  i=14

fsolve(p[14][2] = VP[14]);

                0.02612014634

Compare with the range  0.01338216460 < x and x <= 0.02612014630

For  i=2

fsolve(p[2][2] = VP[2]);

       0.4793595141

The corresponding range  0.3166653569 < x and x <= 0.4793595141

@acer  Thank you very much for the detailed analysis of the situation with floats.

@Markiyan Hirnyk  Your example does not contradict anything. By default  Digits=10 so

is(4.=4.+10^(-20));

              true

Or use quotes:

plot( 'myproc(300,V)', V=0.1..0.9 );

Maximize(
'myproc(300,v)',
v=0.00001..0.99999
);

@acer   Thanks for  Explore ! This tool is very interesting. I did not know (as well as Rouben) about it.

@mathnoob1  For clarity, you can make all the different colors: text in black (by default), 2d-math input in red, output in blue (by default).

Example:

and so on.

See the solution here

@abbeykabir  The error in the line   y[j]:= y + h*fxy(a,b):

The name of indexed variable  y[j]  coincides with formal parameter  y
 

@smith_alpha   

f:=x^2*exp(-1.2*x);

M:=[maximize(f, x=0..100, location)];

a:=M:  L:=[2,1,1,1,2]:

for i in L do

a:=op(i, a);

od;

Of course, all these steps I'm doing in the mind.