## 703 Reputation

18 years, 107 days

## Matrix in Matrix...

This gives the same result as your example

`Matrix(3, (i,j) -> `if`(i <= j, Matrix(2, [seq(x[i,j], k = 1 .. 4)]), Matrix(2)));`

Duncan

## Nextprime or Randprime...

Nextprime is one possibility n := 300; p := x^n; p := Nextprime(p, x) mod 2; while Primitive(p) mod 2 = false do p := Nextprime(p, x) mod 2; end do; Primitive(p) mod 2; Randprime is another possibility n := 20: p := Randprime(n, x) mod 2; while Primitive(p) mod 2 = false do p := Randprime(n, x) mod 2; end do; Primitive(p) mod 2;

## Use SubVector...

The LinearAlgebra package provides the SubVector command to construct a subvector of a Vector:

```v := <9,8,5,7>:
n := 4:
v2 := LinearAlgebra:-SubVector(v, [1 .. n-1, n+1 .. -1]); # remove the n'th entry
[9]
[ ]
v2 := [8]
[ ]
[5]

```

To remove several entries at once:

```A:=<4,5,3,0,8,12>:
elim := [2,3,5]:
idx := [\$ 1 .. LinearAlgebra:-Dimension(A)]; # The indices of 'A' in increasing order

idx := [1, 2, 3, 4, 5, 6]```
```
keep := subsop(seq(i=NULL, i in elim), idx);
keep := [1, 4, 6]```
```
v3 := LinearAlgebra:-SubVector(A, keep);
[ 4]
[  ]
v3 := [ 0]
[  ]
[12]

```

## Using Maple on console...

The "save" command can be used to save assigned names to a file. The help page for this command can be found by typing

?save

at a command prompt. The "read" command can be used to read a saved file. "writeto" and "appendto" may also be useful.

## Importing an Excel Worksheet into Maple...

The Import command from the ExcelTools package can be used to import an Excel worksheet into Maple.

## Empty plot...

The function should be defined as `f:=x->1-abs(x);` instead of `f(x):=1-abs(x);` and the font options (`labelfont` and `font`) used in the plot command should be uppercase, e.g., `[HELVETICA, BOLD, 12]`. Duncan

## Hankel transform...

The literal translation of Integral{f(t)*Jn(s*t)*t dt, t:0->inf} into Maple code is `int(f(t) * BesselJ(0, s*t) * t, t = 0 .. infinity);`. For `f(t)=exp(-Pi*t^2)`, `int(exp(-Pi*t^2) * BesselJ(0, s * t) * t, t = 0 .. infinity);` gives `(1/2)*exp(-(1/4)*s^2/Pi)/Pi`. To reduce the number of factors of `2*Pi`, an alternative version of the transform is `2 * Pi * int(exp(-Pi*t^2) * BesselJ(0, 2 * Pi * s * t) * t, t = 0 .. infinity);`

## Microsoft Visual C++ 2008 Express Editio...

If you are a Windows user you can download Microsoft Visual C++ 2008 Express Edition free from Microsoft's website and configure it to edit .mpl files and call Command-line Maple with your .mpl files as an argument.

After installing MSVC++  Express Edition, select Tools > External Tools from the menu system. In the resulting pop-up box, click the "Add" button to add a new menu item then enter the following.

Title:    &Maple

Command:    C:\Program Files\Maple 12\bin.win\cmaple.exe   (or whatever the path is to your Command-line Maple executable)

Arguments:    \$(ItemFileName)\$(ItemExt)

Initial directory:    \$(ItemDir)

Then click "Ok"

This will add a "Maple" menu item to the Tools menu. You can then edit .mpl files in the editor. After saving, select Tools > Maple from the menu system and the .mpl file will execute in Command-line Maple.

Duncan

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