
Re: NSolve output
Posted:
Jan 14, 2013 12:00 AM


$Version
"9.0 for Mac OS X x86 (64bit) (November 20, 2012)"
a = x z + 2 x y + 2 y z; v = x y z;
a2 = a /. x > 2 z; v2 = v /. x > 2 z;
NSolve[{a2 == 60, v2 == 40, x == 2 z, x > 0}, {x, y, z}]
{{x > 5.1156, y > 3.05701, z > 2.5578}, {x > 7.46083, y > 1.43719, z > 3.73042}}
Solve[{a2 == 60, v2 == 40, x == 2 z, x > 0}, {x, y, z}, Reals] // N
{{x > 5.1156, y > 3.05701, z > 2.5578}, {x > 7.46083, y > 1.43719, z > 3.73042}}
{Reduce[{a2 == 60, v2 == 40, x == 2 z, x > 0}, {x, y, z}, Backsubstitution > True] // N // ToRules}
{{x > 5.1156, y > 3.05701, z > 2.5578}, {x > 7.46083, y > 1.43719, z > 3.73042}}
Bob Hanlon
On Sat, Jan 12, 2013 at 9:53 PM, Berthold Hamburger <bhamburger@artinso.com> wrote: > Hello, > > I want to solve two simple equations with NSOLVE to calculate the > dimensions of a rectangular box that is open on top. The length of the > box is twice the width and the volume and area of the box are > respectively 40 cubic feet and 60 square feet. > > I defined the area and volume: > a = xz + 2xy + 2yz > v = xyz > > then substituted x with 2z: > > a2 = a /. x>2z > v2 = v /. x>2z > > > > a2 = 6 y z + 2 z^2 > v2 = 2 y z^2 > > solved with NSolve: > step1 = NSolve[{a2 == 60, v2 == 40}, {y, z}, Reals] [[1,2]] //Column > > which returns the results > {y>3.05701,z>2.5578} > > I would like to get an output that returns values for all 3 variables > x,y,z as in > > {x>5.1156,y>3.05701,z>2.5578} > > but somehow cannot find a way to do it > > What would be the correct way for doing that? > > Regards > > Berthold Hamburger >

