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Feb
9
comment Calculate area under a polyline
@MichaelE2 If I change the code into tmp = {{0, 0}, {1, 1}, {2, 1}, {3, 2}, {1, 6}}; plot = ListLinePlot[tmp, Filling -> Axis]; Area@DiscretizeGraphics[plot] I got the answer is 8. My maple has the same result. But your code is 6. I don't understand why?
Dec
23
comment How to select a list from a list?
I am sorry. I did.
Dec
23
comment How to select a list from a list?
If each element contains four points, for example, {{-5, -1, -1}, {-5, -1, 3}, {-5, 4, -2}, {3, -1, -5}}. I tried Select[nonright, (12 == Length[Union @@@ #] &)] it does not correct. Please help me.
Dec
22
comment How to select a list from a list?
Thank you very much.
Dec
22
comment How to select a list from a list?
@ belisarius In line Select[lst, ( 9 == Length[Union @@ #] &)] If I want 9 numbers different from 0. How can I select?
Dec
21
comment How to select a list from a list?
Yes. I will edit my question.
Dec
21
comment How to select a list from a list?
You understand me. Thank you very much.
Jul
17
comment Is this a bug in FunctionDomain (V.10)?
Mclure First, thanks to your answer. I think, we want to find the domain of the given function, we must solve the inequality x^3+1<>0.
Jun
24
comment How do I calculate the area of a polygon given its coordinates?
Thank you very much.
Jun
24
comment How do I calculate the area of a polygon given its coordinates?
when I tried pts = {{5, 2}, {4, 1}, {1, 3}}; GraphicsMeshMeshInit[]; PolygonArea[pts] I got -2.5. I don't understand.
Jun
24
comment How do I obtain the enclosed area of this particular parametric plot?
I tried pts = {{5, 2}, {4, 1}, {1, 3}}; GraphicsMeshMeshInit[]; PolygonArea[pts] but I received -2.5
Jun
23
comment How can I get the exact real solution of this equation?
Let us continue this discussion in chat.
Jun
23
comment How can I get the exact real solution of this equation?
I am a teacher. When I teach for my students, in this case, when we solve by hand, we always conclude the given solution has only real solution (solve in real domain). Am I wrong?
Jun
23
comment How can I get the exact real solution of this equation?
Thank you very much for your answers and your helps.
Jun
23
comment How can I get the exact real solution of this equation?
Perhaps about my English, therefore my question is not clearly. My question is "How many solutions when I solve the equation Sqrt[x] + Sqrt[1 - x^2] == Sqrt[2 - 3 x - 4 x^2] in the real domain?
Jun
23
comment How can I get the exact real solution of this equation?
I have just online. Thank you four your answer.
Jun
23
comment How can I get the exact real solution of this equation?
I used Solve[Sqrt[x] + Sqrt[1 - x^2] == Sqrt[2 - 3 x - 4 x^2], x, Reals] // ToRadicals, then I got one real solution.
Jun
23
comment How can I get the exact real solution of this equation?
@MichaelE2 I use Solve[Sqrt[x] + Sqrt[1 - x^2] == Sqrt[2 - 3 x - 4 x^2], x, Reals] // ToRadicals and received one real solution. Thank you.
Jun
23
comment How can I get the exact real solution of this equation?
@Artes With Maple, I received one real solution. For me, the given equation has only one real solution.
Jun
23
comment How can I get the exact real solution of this equation?
@belisarius and @Algohi, with -1 - Sqrt[2], the Sqrt[-1 - Sqrt[2]]is not identified.