2
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A huge set of conditions

    cond={1440 (eta + 2 xsi) (9.81 + 0.003969 (1 + zeta)) >= 
  114.307 (1 + zeta), 
 114.307 (1 + zeta) >= 
  1440 (eta - 2 xsi) (9.81 + 0.003969 (1 + zeta)), 
 1440 (9.81 (2 + eta - 2 xsi) + 
     0.0068431 (-11.6 + 0.58 (eta - 2 xsi)) (1 + zeta)) >= 0, 
 1440 (9.81 (-2 + eta + 2 xsi) + 
     0.0068431 (-11.6 + 0.58 (eta + 2 xsi)) (1 + zeta)) <= 
  0, -783.333 <= -0.275369 (78.2399 eta + 1560.9 (-1 + xsi) - 
     3.90224 (1 + xsi)), -0.275369 (78.2399 eta + 1560.9 (-1 + xsi) - 
     3.90224 (1 + xsi)) <= 783.333, -783.333 <= 
  0.249143 (78.2399 eta + 1560.9 (-1 + xsi) - 3.90224 (1 + xsi)), 
 0.249143 (78.2399 eta + 1560.9 (-1 + xsi) - 3.90224 (1 + xsi)) <= 
  783.333, 2482.76 (0.000443649 (78.2399 eta + 1560.9 (-1 + xsi) - 
        3.90224 (1 + xsi)) + 0.0184162 (1 + zeta) - 
     0.232 (eta + 2 xsi) (9.81 + 0.003969 (1 + zeta))) <= 0, 
 2482.76 (-0.000443649 (78.2399 eta + 1560.9 (-1 + xsi) - 
        3.90224 (1 + xsi)) + 0.0184162 (1 + zeta) - 
     0.232 (eta + 2 xsi) (9.81 + 0.003969 (1 + zeta))) <= 0, 
 2482.76 (-0.000401397 (78.2399 eta + 1560.9 (-1 + xsi) - 
        3.90224 (1 + xsi)) + 
     0.4 (-0.0460404 (1 + zeta) + 
        0.58 (eta - 2 xsi) (9.81 + 0.003969 (1 + zeta)))) <= 0, 
 2482.76 (0.000401397 (78.2399 eta + 1560.9 (-1 + xsi) - 
        3.90224 (1 + xsi)) + 
     0.4 (-0.0460404 (1 + zeta) + 
        0.58 (eta - 2 xsi) (9.81 + 0.003969 (1 + zeta)))) <= 0}

define a region in 3D

I would like to create a RegionPlot3D

RegionPlot3D[ AllTrue[cond], {xsi, 0, 1}, {eta, -1, 1}, {zeta, -1, 20} ]

but Mathematica doesn't evaluate.

What could be the reason ? Is there a workaround?

Thanks!

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7
  • 3
    $\begingroup$ RegionPlot3D[And @@ cond, {xsi, 0, 1}, {eta, -1, 1}, {zeta, -1, 20}] ? $\endgroup$
    – Syed
    Jan 29 at 16:50
  • 1
    $\begingroup$ @Syed Such a simple solution, thank you very much. Couldn't step away from my AllTrue attempt... $\endgroup$
    – Ulrich Neumann
    Jan 29 at 16:59
  • $\begingroup$ @Syed Followup problem: Is it possible to extract the "Volume" as an implicit region from a given RegionPlot3D ? Thank You! $\endgroup$
    – Ulrich Neumann
    Jan 30 at 11:05
  • $\begingroup$ reg = ImplicitRegion[And @@ cond, {xsi, eta, zeta}]; and Volume@reg gives 3.11594 and the RegionMeasure[reg, 3] gives the same result, albeit with some delay. I don't have enough insight to say if it is correct, but you can provide feedback. Thanks. $\endgroup$
    – Syed
    Jan 30 at 11:11
  • $\begingroup$ @Syed Thanks for your fast response. Unfortuantely Region[reg] only shows a blanc cell. $\endgroup$
    – Ulrich Neumann
    Jan 30 at 11:16

1 Answer 1

Reset to default
3
$\begingroup$ 
RegionPlot3D[And @@ cond, {xsi, 0, 1}, {eta, -1, 1}, {zeta, -1, 20}]

OR

RegionPlot3D[
 AllTrue[cond, # == True &], {xsi, 0, 1}, {eta, -1, 1}, {zeta, -1, 
  20}]

enter image description here

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1
  • $\begingroup$ RegionPlot3D[ AllTrue[cond, Identity], {xsi, 0, 1}, {eta, -1, 1}, {zeta, -1, 20}] would also work and look less awkward. $\endgroup$
    – Syed
    Jan 29 at 18:55

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