## 110 Reputation

4 years, 200 days

## Derivative with numerical method...

Maple 2019

 >
 >
 >
 >
 >
 (1)
 >
 (2)
 >
 (3)

Using numerical methods, I cannot calculate the derivative of sd with respect to r at r = 2 and t = 4.

Oliveira.

 >

## Dirichlet conditions and Neumann values...

Maple 2019

Does anyone know how to enter in the pdsolve function Dirichlet conditions and Neumann values?

Oliveira.

## Combining and converting units...

Maple 2019

 >

Note: To enter units, I used the unit key (blue) in the Units palette.

When I use the combine and simplify functions to manipulate temperature units, Maple returns a wrong answer, as we can see below;

 >
 (1)
 >
 (2)

The quantity 20 Celsius is not converted correctly. However, for other types of dimensions, the combine and simplify functions work correctly.

 >
 (3)
 >
 (4)
 >

Another strange thing happens with the convert function, with temperature units. When we use the same source unit, the convert function deletes the unit, leaving only the quantity.

 >
 (5)

I do not understand why this occurs.

 >
 (6)

I do not understand why this occurs.

Oliveira

Maple 2019

In the DE solution below I cannot convert the RootOf function to radicals.
macro(solve = allvalues@solve);
_EnvExplicit := true;
de := x^4*diff(y(x), x \$ 2) + omega^2*y(x) = 0;
bc := y(a) = 0, y(b) = 0, D(y)(a) = 1;
dsol := (dsolve({bc, de}, {omega, y(x)}) assuming (0 < a, a < b));
{omega = RootOf(tan(_Z)*_Z*b*_C2 - sin(-2*_B5*Pi + 2*Pi*_Z10 + 2*_B5*arccos(_Z*b*_C2/a) - arccos(_Z*b*_C2/a))*a)*b, y(x) = x*(-cos(RootOf(tan(_Z)*_Z*b*_C2 - sin(-2*_B5*Pi + 2*Pi*_Z10 + 2*_B5*arccos(_Z*b*_C2/a) - arccos(_Z*b*_C2/a))*a)*b/x)*sin(-2*_B5*Pi + 2*Pi*_Z10 + 2*_B5*arccos(RootOf(tan(_Z)*_Z*b*_C2 - sin(-2*_B5*Pi + 2*Pi*_Z10 + 2*_B5*arccos(_Z*b*_C2/a) - arccos(_Z*b*_C2/a))*a)*b*_C2/a) - arccos(RootOf(tan(_Z)*_Z*b*_C2 - sin(-2*_B5*Pi + 2*Pi*_Z10 + 2*_B5*arccos(_Z*b*_C2/a) - arccos(_Z*b*_C2/a))*a)*b*_C2/a))*a/(RootOf(tan(_Z)*_Z*b*_C2 - sin(-2*_B5*Pi + 2*Pi*_Z10 + 2*_B5*arccos(_Z*b*_C2/a) - arccos(_Z*b*_C2/a))*a)*b) + sin(RootOf(tan(_Z)*_Z*b*_C2 - sin(-2*_B5*Pi + 2*Pi*_Z10 + 2*_B5*arccos(_Z*b*_C2/a) - arccos(_Z*b*_C2/a))*a)*b/x)*_C2)}

Does anyone know how to convert the above expression to radicals?
I'm grateful.
Oliveira

In the DE solution below I cannot convert the RootOf function to radicals.

 >
 >
 >
 >
 >
 >
 (1)

Does anyone know how to convert the above expression to radicals?
I'm grateful.

Oliveira

## uses function with the Physics package...

Maple 2019

When I apply the uses function with the Physics package in a procedure, the commands in this package are not restricted to the inside of the procedure, but are applied globally. See the example below:

gds := proc(LL, qi, t)

local ta,i;

uses Physics;

ta := sec(diff(diff(LL, diff(qi[i](t), t)), t), i = 1 .. nops(qi));

RETURN(ta) end:

sxy := diff(x(t), t)^2 + diff(y(t), t)^2:

gds(sxy, [x, y], t);

Error, (in Physics:-diff) name expected for external function

On the other hand, when I apply the uses function with the LinearAlgebra package in a procedure, the commands in this package are restricted to the inside of the procedure only.
dst:=proc(MM)

local DA;

uses LinearAlgebra;

DA:=Determinant(MM);

RETURN(DA) end:

dst(<<1 | 2>, <3 | 4>>);

-2

Determinant(<<1 | 2>, <3 | 4>>);

Determinant(Matrix(2, 2, [[1, 2], [3, 4]]))

This could be a bug in Maple 2019?

 1 2 3 4 Page 1 of 4
﻿