Edit 1Edit 1:
Issues seem to emerge from within ImplicitRegion
as well as Region Plot
.
Using $Surd[y^{2},{3}]$ or avoiding $y^{2/3}$ by using $y^{3}$ will result in a correct result of Integrate
. Also Area
and Integrate
seem to return identical results.
In other case both the results of RegionPlot
or Integrate[1,Element[{x,y},reg]
of the following ImplicitRegion
will be wrongwrong, as verified by last result (In case no mistake was done):
$\text{reg7}=\text{ImplicitRegion}\left[\sin [x]\leq y\leq \cos [x],\left\{\left\{x,0,\frac{3 \pi }{2}\right\},y\right\}\right] $
The results and double checking them unfold as follows:
$\text{RegionPlot}[\text{reg7}]$
$\text{Integrate}[1,\{x,y\}\in \text{reg7}]$
$2 \left(\sqrt{2}-1\right)$
$\int_0^{\frac{3 \pi }{2}} \text{Abs}[ \cos [x]-\sin [x]] \, dx$
$2 \left(2 \sqrt{2}-1\right)$
Original Post:
I am trying to Integrate the area mentioned below using ImplicitRegion function, following this resource. This method worked in many other scenario. The plot was accurate, but the integration returned 1/10 which is not true as is verified by the traditional integration. I have tried integration over $-1\leq y\leq 0$ and $0\leq y\leq 1$ separately and also using Surd[x,3]^2 but things got much weirder. Can any one give a hint how I can improve or correct this?
$\text{reg}=\text{ImplicitRegion}\left[y\leq x\leq y^{\frac{2}{3}},\{x,\{y,-1,1\}\}\right]$
$\text{RegionPlot}[\text{reg}]$
$\text{Integrate}[1,y\in \text{reg}]$
$\frac{1}{10}$
$\int_{-1}^1 \left(y^{\frac{2}{3}}-y\right) \, dy$
$\frac{3}{5} \left(1+(-1)^{2/3}\right)$