## 490 Reputation

8 years, 262 days
Maple is to me difficult. The first version I bought was Maple9, and it was more than 15 years ago. But, I couldn't use it, feeling it too difficult. But, three years ago, I thought Maple might be helpful to my study, and since then, I have continued to learn Maple. As I got able to read the Maple help, I think that I could get to use maple better now than before. But, I feel that I am a beginner yet.

## How to use GRID in PLOT3D?...

Maple

Hello people in MaplePrimes,

I can't understand a code with PLOT3D using GRID in it.
I hope you will give me explanation about it.

```restart;
k:=[[1,2,10],[1,1,8],[0,1,5],[0,0,6]];
PLOT3D(GRID(1..2,1..3,k),
AXESLABELS(x,y,z));
```

I cannot understand the correspondence between points in the graph and lists in the code such as [1,2,10], [1,1,8].

As two ranges in GRID augments in the code are 1..2 and 1..3, x takes value from 1 to 2, and
y from 1 to 3 in the picture.
And, as k is k:=[[1,2,10],[1,1,8],[0,1,5],[0,0,6]], which means this list of lists are 4 X 3, so in the picture
as for x the interval of 1 to 2 is divided to three sections with the points of value of 0, 1/3, 2/3 and 3/3, which total number is 4.
And, as for y the interval of 1 to 3 is devided to two sections with the points of value of 1, 2 and 3, which total number is 3.

And, I cannot understand why from the grid of [1,1,8] in the code, which I think is the coodinate of (1, 1) on x-y plane, does not mean that the value of z on that point on the graph is not 8, but 1.

graph.mw

## procedure in ribbonplot...

Maple 2021

Hello people in Mapleprimes,
I haven't written in this site for a long time.

I have a question in the below program, which is to write ribbons.
For the implementation of this program,
I wrote this.
ribbonplot5([cos, sin, cos + sin], -Pi .. Pi,numpoints=20);

In the part of pattern matching, as -Pi .. Pi above is a range, so it is OK.
But, when I changed this part to x=-Pi..Pi, an error message appears.

ribbonplot5([cos, sin, cos + sin],x=-Pi .. Pi,numpoints=20);

brings error messages:
"Warning, unable to evaluate the function to numeric values in the region; see the plotting command's help page to ensure the calling sequence is correct"

In the code of ribbonplot5,  x=-Pi..Pi which is the type of name=range shoud satisfy the pattern matching, as I wrote in the first part of the program as
ribbonplot5 := proc(Flist, r1::{range,name=range})

I cannot know why the part of the program:

" else
newFlist := map(unapply, Flist, lhs(r1));
opts := ['labels'=[lhs(r1), " "," "],
args[3 .. nargs]];
ribbonplot5(newFlist,rhs(r1),op(opts)):
"

wouldn't work well.

I wish I could get an answer to this.

This is a program in maple9 Advanced Programming Gude p. 253

graphic_ribbonplot.mw

```restart;
extend := proc(f)
local x, y;
unapply(f(x), x, y);
end proc:
p:=x->cos(2*x):
q:=extend(p);

ribbonplot5 := proc(Flist, r1::{range,name=range})
local i, m, p, n, opts,newFlist;
opts := [args[3 .. nargs]];
if type(r1, range) then
if not hasoption(opts, 'numpoints', 'n', 'opts')
then n := 25
end if;
m := nops(Flist);
p := seq(plot3d(extend(Flist[i]), r1, (i-1) .. i,
grid=[n, 2], op(opts)),
i = 1 .. m):
plots[display](p):
else
newFlist := map(unapply, Flist, lhs(r1));
opts := ['labels'=[lhs(r1), " "," "],
args[3 .. nargs]];
ribbonplot5(newFlist,rhs(r1),op(opts)):
end if:
end proc:
ribbonplot5([cos, sin, cos + sin], -Pi .. Pi,numpoints=20);
```

## Fractional expression simplification...

Maple 2019

Dear people in mapleprims,

I haven't used maple for a long time.
By the way, I tried to modify a denominator part in an fractional expression, but I couldn't.

Original expression is

a:=-(I__22-X__2)/(I__11*I__22-I__11*X__2-I__12*I__21-I__22*X__1+X__1*X__2);

#And, I want to change this to the form

b:=(X__2-I__22)/((x__1-I__11)*(X__2-I__22)-I__12*I__21);

How can I do this?

## Modifying an equation containing w^sigma...

Maple 2019

Hello people in mapleprimes,

I could modify an expression e_n_1b to simpler e_n_1e as is in attached file.
Is there any other way to change e_n_1b into e_n_1e?

Dec_22.mw

taro

## Substitution_of_variable_into_equations...

Maple 2019

Hello people in Mapleprimes,

A long time has passed since I came here before.
I have forgotten a lot of what I remembered about maple.

I want to incert gamma from e_nsp1 and (1-gamma) from e_nsp2 into set_3, so deleting gamma and (1-gamma) from set_3.
How can I do this?

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