In OpenMDAO how to specify values to IndepVarComp or other components? - openmdao

Question

I am just playing around with the Paraboloid tutorial in OpenMDAO. I tried something simple, basically changing the input values to the Paraboloid component. See the following code. When I run it though, it will print the same result as if nothing happened. So what is going on? if I have a group, how would I modify the inputs?
from __future__ import print_function
from openmdao.api import IndepVarComp, Component, Problem, Group
class Paraboloid(Component):
""" Evaluates the equation f(x,y) = (x-3)^2 + xy + (y+4)^2 - 3 """
def __init__(self):
super(Paraboloid, self).__init__()
self.add_param('x', val=0.0)
self.add_param('y', val=0.0)
self.add_output('f_xy', val=0.0)
def solve_nonlinear(self, params, unknowns, resids):
"""f(x,y) = (x-3)^2 + xy + (y+4)^2 - 3
"""
x = params['x']
y = params['y']
unknowns['f_xy'] = (x-3.0)**2 + x*y + (y+4.0)**2 - 3.0
def linearize(self, params, unknowns, resids):
""" Jacobian for our paraboloid."""
x = params['x']
y = params['y']
J = {}
J['f_xy', 'x'] = 2.0*x - 6.0 + y
J['f_xy', 'y'] = 2.0*y + 8.0 + x
return J
if __name__ == "__main__":
top = Problem()
root = top.root = Group()
root.add('p1', IndepVarComp('x', 3.0))
root.add('p2', IndepVarComp('y', -4.0))
root.add('p', Paraboloid())
root.connect('p1.x', 'p.x')
root.connect('p2.y', 'p.y')
root.p1.x=3.0;
root.p2.y=-4.0;
top.setup()
top.run()
print(root.p.unknowns['f_xy'])
root.p1.x=5.0;
root.p2.y=5.0;
top.setup()
top.run()
print(root.p.unknowns['f_xy'])

Answer 1

You have to call setup() before you can set any values.
After that you set them via a dictionary like access from the problem instance. For your sample code it should look like:
top.setup()
top['p1.x'] = 3.
top['p2.y'] = 4.
top.run()
print(top['p.f_xy'])
top['p1.x'] = 10.
top['p2.y'] = 10.
top.run()
print(top['p.f_xy'])
When I run this model with the adjusted script I get:
##############################################
Setup: Checking for potential issues...
No recorders have been specified, so no data will be saved.
Setup: Check complete.
##############################################
73.0
342.0