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C_R

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5 years, 182 days
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These are questions asked by C_R

Why can't the commands in these document...

C_R 3042 Maple 2023
document-block
March 13 2023
0 0

 

ODE for electrical circuit (right click on Documentblock, unselect show command does not work. Command still visble)u(t) = T*(diff(`ϕ`(t), t))+L*(diff(i(t), t))+i(t)*R

u(t) = T*(diff(varphi(t), t))+L*(diff(i(t), t))+i(t)*R

 (1)

 

ODE for motor (toggle Documentblock, unselect show command is only effective on equations  3 and 4)i(t)*T = J*(diff(`ϕ`(t), t, t))

i(t)*T = J*(diff(diff(varphi(t), t), t))

 (2)

Isolate i(t) and taking the derivative

i(t) = J*(diff(diff(varphi(t), t), t))/T

 (3)

``

diff(i(t), t) = J*(diff(diff(diff(varphi(t), t), t), t))/T

 (4)

``

Download Document_Block_hide_command.mw

Some unit questions about angles...

C_R 3042 Maple
units radians
March 11 2023
0 3

Q1: In the above, why can I only convert radians to radians. Or: Why does the menu "Chose unit" not offer arcdeg?

Q2: In the above, why is nothing happening when I enter arcdeg in the field "Enter Unit"?

Q3: How to change the displayed symbol for arcdeg to ° (in the attachment are failed attempts)?

arcdeg.mw

How to shift the index in a sum...

C_R 3042 Maple
sum index
March 06 2023
3 5

For example from

sum(a[k]*(k+r)*(k+r-1)*x^(k+r-1), k = 0 .. infinity)

sum(a[k]*(k+r)*(k+r-1)*x^(k+r-1), k = 0 .. infinity)

 (1)

by substituting k by k+1 to

sum(a[k+1]*(k+1+r)*(k+r)*x^(k+r), k = -1 .. infinity)

sum(a[k+1]*(k+1+r)*(k+r)*x^(k+r), k = -1 .. infinity)

 (2)

Doing

subs(k = k+1, sum(a[k]*(k+r)*(k+r-1)*x^(k+r-1), k = 0 .. infinity))

sum(a[k+1]*(k+1+r)*(k+r)*x^(k+r), k+1 = 0 .. infinity)

 (3)

leads to output that can't be processed further  

subsop(2 = 'k = -1 .. infinity', sum(a[k+1]*(k+1+r)*(k+r)*x^(k+r), k+1 = 0 .. infinity))

Error, (in sum) second argument must be a name, name=a..b, name=RootOf, or name=algebraic

  

NULL

Doing it programmatically this way

shift := k = k+1; rsd := (lhs-rhs)(shift); subs(shift, [op(sum(a[k]*(k+r)*(k+r-1)*x^(k+r-1), k = 0 .. infinity))]); lhs(%[2])+rsd = map(`+`, rhs(%[2]), rsd); sum(subsop(2 = %, `%%`)[])

sum(a[k+1]*(k+1+r)*(k+r)*x^(k+r), k = -1 .. infinity)

 (4)

is not realy elegant and easy to understand.

Download shifting_index_in_sums.mw

Are there better ways?

Why no warning is returned with 2D input...

C_R 3042 Maple 2023
integration int warning
February 19 2023
0 5

(Deleted because not reproducible on a different PC)

With 1D

> 

int(1/(sqrt(x__0 - x)*sqrt(-x^2 + 1)), x = 0 .. x__0)

Warning, unable to determine if -1 is between 0 and x__0; try to use assumptions or use the AllSolutions option

  

Warning, unable to determine if 1 is between 0 and x__0; try to use assumptions or use the AllSolutions option

  

int(1/((x__0-x)^(1/2)*(-x^2+1)^(1/2)), x = 0 .. x__0)

 (1)
> 

NULL

With 2D

int(1/(sqrt(x__0-x)*sqrt(-x^2+1)), x = 0 .. x__0)

int(1/((x__0-x)^(1/2)*(-x^2+1)^(1/2)), x = 0 .. x__0)

 (1)

NULL

The root cause might be the same as for this open question.

int_warning_2D.mw

int_warning_1D.mw

Some questions about suppression of warn...

C_R 3042 Maple
warning
February 17 2023
1 2

Q1: Is it possible to find out where a warning was generated (i.e. which procedure issued the warning)?

Q2: Is a command specific warning suppression possible? Something like that for example: infolevel[int] := 0

Q3: Can warnings be removed form a document before printing it?

Typical warnings I want to suppress are attached
 

Download warnings_to_suppress.mw

Update: for the attached warnings Typesetting:-Settings(parserwarnings = false) is effective, which does not work for warnings discussed bellow.

 

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