PART CMD

Jaime shared this idea 6 years ago

Completed

Hi, I want to get the first part of the factorization (x - 3) * (x + 1) -> (x - 3) on row #4 , xCAS have a command called PART, but it seems that it is not available in GG, please GG Development group, add this super important function

Thanks

PART CMD info

http://www-fourier.ujf-gren...

CAS VIEW (GG)

1: x^2 = 2*x + 3 -> x^2 = 2*x + 3

2: $1 - (2x + 3) -> x^(2) - (2 * x) - 3 = 0

3: Factor[LeftSide[$2]] -> (x - 3) * (x + 1)

4: part( (x - 3) * (x + 1), 1 ) -> (x - 3)

I like this idea

Comments (6)

Michel Iroir ● 6 years ago

You like the Parisse's job within giac, you'll like the Parisse's and other developers job within GeoGebra smile

Try :

4: Element[$3,1]

and/or :

4:Element[Factors[LeftSide[$2]],1,1]

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Jaime ● 6 years ago

Ok, the following sequence of statements, show step by step the solution of a simple list of equations.

In line 10 , how can I get "9=9 -> true" by manipulating the responses of the previous outputs.

Try the following but fail

LeftSide[$9] ≟ RightSide[$9]

{ y = x^2, y = 2*x + 3 } -> { y = x^2, y = 2*x + 3 }
Substitute[Element[$1,2],Element[$1,1]] -> x^(2) = (2 * x) + 3
$2 - (2x + 3) -> x^(2) - (2 * x) - 3 = 0
Factor[LeftSide[$3]] -> ((x - 3) * (x + 1))
{Element[$4,1] = 0, Element[$4,2] = 0} -> {x - 3 = 0, x + 1 = 0}
{Element[$5,1] + 3, Element[$5,2] - 1} -> {x = 3, x = (-1)}
Substitute[Element[$1,1],Element[$6,1]] -> y=9
Substitute[Element[$1,2],Element[$6,1]] -> y=9
Substitute[Element[$1,1],{$8, Element[$6,1]}] -> 9=9
$9 -> true

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Michel Iroir ● 6 years ago

Hi, I don't understand why

LeftSide[$9] ≟ RightSide[$9]

and LeftSide[$9] ≟ RightSide[$9]+0

fail while :

LeftSide[$9]+0 ≟ RightSide[$9]

and LeftSide[$9] - RightSide[$9] ≟ 0

work fine

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Jaime ● 6 years ago

then, Is an interpretation not yet incorporated or bug?

For GG TEAM

To check this type of expression, please include the EvalBoolean command of Xcas

Xcas: CAS view

1: 9=9 returns 9=9

2: evalb(ans(-1) ) returns 1 -> true

http://www-fourier.ujf-gren...

full sample

x^2 = 2*x + 3 returns x^2=(2*x+3)
ans(-1) - (2*x + 3) returns x^2-2*x-3=0
factor(ans(-1)) returns (x-3)*(x+1)=0
[ part(left(ans(-1)),1)=0, part(left(ans(-1)),2)=0 ] returns [x-3=0,x+1=0]
ans(-1)(1)+3, ans(-1)(2)-1 ] returns [x=3,x=-1]
subst(y=x^2,ans(-1)(1)) returns y=9
subst(y=2*x + 3,ans(-2)(1)) returns y=9
subst(y=2*x + 3,[ans(-3)(1),ans(-1)]) returns 9=9
evalb(ans(-1)) returns 1 (true)

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Michael Borcherds ● 6 years ago

I think this is what you need:

$7==$8

Please make sure you use the new version (5.0.354.0) which has a couple of related bugs fixed

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Jaime ● 6 years ago

In the version (5.0.354.0) works correctly

9=9 returns 9=9
LeftSide[$1] ≟ RightSide[$1] → true

As an additional idea, please GG TEAM add the ANSWER[row] command as synonymous with the $row command to make the instruction sequences in the CAS view more understandable

with $ cmd

{ y = x^2, y = 2*x + 3 } → { y = x^2, y = 2*x + 3 }
Substitute[Element[$1,2],Element[$1,1]] → x^(2) = (2 * x) + 3
$2 - (2x + 3) → x^(2) - (2 * x) - 3 = 0
Factor[LeftSide[$3]] → ((x - 3) * (x + 1))
{Element[$4,1] = 0, Element[$4,2] = 0} → {x - 3 = 0, x + 1 = 0}
{Element[$5,1] + 3, Element[$5,2] - 1} → {x = 3, x = (-1)}
Substitute[Element[$1,1],Element[$6,1]] → y=9
Substitute[Element[$1,2],Element[$6,1]] → y=9
Substitute[Element[$1,1],{$8, Element[$6,1]}] → 9=9
LeftSide[$9] ≟ RightSide[$9] -> true

with ANSWER CMD

{ y = x^2, y = 2*x + 3 } → { y = x^2, y = 2*x + 3 }
Substitute[Element[answer[1],2],Element[answer(1),1]] → x^(2) = (2 * x) + 3
answer[2] - (2x + 3) → x^(2) - (2 * x) - 3 = 0
Factor[LeftSide[answer[3]]] → ((x - 3) * (x + 1))
{Element[answer[4],1] = 0, Element[answer[4],2] = 0} → {x - 3 = 0, x + 1 = 0}
{Element[answer[5],1] + 3, Element[answer[5],2] - 1} → {x = 3, x = (-1)}
Substitute[Element[answer[1],1],Element[answer[6],1]] → y=9
Substitute[Element[answer[1],2],Element[answer[6],1]] → y=9
Substitute[Element[answer[1],1],{answer[8], Element[answer[6],1]}] → 9=9
LeftSide[answer[9]] ≟ RightSide[answer[9]] → true

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