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[diderot] View of /branches/charisee/ertest/vispaper/gmiso2d/gmiso2d.diderot
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View of /branches/charisee/ertest/vispaper/gmiso2d/gmiso2d.diderot

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Revision 2870 - (download) (annotate)
Wed Feb 25 21:47:43 2015 UTC (4 years, 7 months ago) by cchiw
File size: 1371 byte(s)
added sqrt,pow, and examples
/*
 $DDRO_HOME/branches/vis12/bin/diderotc --exec gmiso2d.diderot \
 && ./gmiso2d \
 && unu jhisto -i x.nrrd -b 800 800 -min 0 0 -max 1 1 \
     | unu 2op neq - 0 \
     | unu quantize -b 8 -o gmiso2d.png
*/
//note my branch doesn't know Inputs, "InputWithDefault"
//input real isoval = 0.5;

real isoval = 0.5;
field#2(2)[] V = bspln3 ⊛ load("../../../data/ddro.nrrd");
field#1(2)[] F = ∇V•∇V - isoval;
field#0(2)[2] gradF = ∇F;




int grid = 150;
int stepsMax = 10;
real epsilon = 0.000001;

strand RootFind(real xi,real yi) {
   output vec2 x = [xi,yi];
   int steps = 0;


   update {
      // Stop if we're no longer inside or taken too many steps.
  
      if (!inside(x, V) || steps > stepsMax)
         die;

        vec2 grad = gradF(x);
        real m=|grad|;
    
      // subsequent expressions are undefined if |∇F| is zero
      if (m == 0.0)
         die;

      // the Newton-Raphson step
       vec2 delta = normalize(grad) * F(x)/m;

      // we've converged if the change is small enough
      if (|delta| < epsilon)
         stabilize;
      x -= delta;
      steps += 1;
   }
}

initially { RootFind(lerp(0, 1, -0.5, ui, grid-0.5),
                      lerp(0, 1, -0.5, vi, grid-0.5))
            | vi in 0..(grid-1), ui in 0..(grid-1) };

/*
 different in 3D:
 vec2 -> vec3
 field#1(2)[] F -> field#1(3)[] F
 initially over 3D grid
*/

root@smlnj-gforge.cs.uchicago.edu
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