docstr: Initialize constants for the system that will be used later.
          
docstr_tok: ["Initialize","constants","for","the","system","that","will","be","used","later","."]
code: def _set_up_system(
      self,
      d1=None,
      d2=None,
      little_m=None,
      big_m=None,
      spring_k1=None,
      spring_k2=None,
      b=None,
      x=None,
      x_dot=None,
      theta=None,
      theta_dot=None,
      px_len=None,
      scale=None,
      pivot=False,
      method="Euler",
      dt=None,
      font_size=None,
  ):
      """Initialize constants for the system that will be used later."""
  
      self.method = (
          string.capwords(method, "-")
          if method.lower() in VALID_METHODS
          else "Euler"
      )
      self.font_size = font_size
      try:
          self.method_text.text = "Method: {}".format(self.method)
          self.method_text.font_size = 2 / 3 * self.font_size
          self.text.font_size = self.font_size
      except AttributeError:
          # Running in __init__, so self.method_text isn't established yet.
          pass
      self.show_pivot = pivot
  
      # Initialize constants for the system
      self.t = 0
      self.dt = 1 / 60 if dt is None else dt
      self.d1 = 0.97 if d1 is None else d1
      self.d2 = 0.55 if d2 is None else d2
      self.little_m = 2.0 if little_m is None else little_m
      self.big_m = 12.5 if big_m is None else big_m
      self.spring_k1 = 1.35 if spring_k1 is None else spring_k1
      self.spring_k2 = 0.5 if spring_k2 is None else spring_k2
      self.b = 25.75 if b is None else b
      self.j_term = (
          (1 / 3)
          * self.big_m
          * (self.d1**3 + self.d2**3)
          / (self.d1 + self.d2)
      )
      self.x = -0.010 if x is None else x
      self.x_dot = -0.12 if x_dot is None else x_dot
      self.theta = 0.005 if theta is None else theta
      self.theta_dot = 0.0 if theta_dot is None else theta_dot
      self.theta_not = self.theta  # I'll need this later
  
      # Initialize constants for display
      self.px_len = 10 if px_len is None else px_len
      self.scale = 50 if scale is None else scale
      self.px_per_m = self.scale * self.px_len / (0.97 + 0.55)
      self.rod_scale = (self.d1 + self.d2) / self.standard_length
  
      # Set up stuff for establishing a pivot point to rotate about
      self.pivot_loc = (self.d2 - self.d1) / 2
      self.pivot_loc_px = self.pivot_loc * self.px_per_m
  
      # Set up positioning info for the springs and mass, as well as some
      # constants for use later
      # NOTE: Springs are not like boxes. Their center of rotation is at one
      #       end of the spring, unlike the box where it is in the middle.
      #       The location and scaling is set to reflect this. This means
      #       there's a little bit of x- and y-translation needed to properly
      #       center them.
      self.s2_loc = np.asarray(
          [
              self.d1 * self.px_per_m * np.sin(self.theta),
              -self.d1 * self.px_per_m * np.cos(self.theta),
          ]
      )
      self.s1_l_not = self.px_len / 4 * self.scale
      self.x_is_0 = (
          -self.d2 * self.px_per_m * np.sin(self.theta_not)
          - 1.5 * self.s1_l_not
      )
      self.s1_loc = np.asarray(
          [
              self.x_is_0
              + 0.5 * self.s1_l_not
              + self.x * self.px_per_m,
              self.d2 * self.px_per_m * np.cos(self.theta),
          ]
      )
      self.mass_loc = np.asarray(
          [
              self.x_is_0 + self.x * self.px_per_m,
              self.d2 * self.px_per_m * np.cos(self.theta),
          ]
      )
  
imports: from __future__ import division, print_function, absolute_import
  from vispy import app, visuals
  from vispy.visuals import transforms
  from vispy.io import load_data_file
  import sys
  import numpy
  import string
  import logging
  import traceback
  from PyQt5 import QtCore, QtGui, QtWidgets
label_desc: Use image node_id 9 for calling the WigglyBar obj's underlying member method code with example usage: obj._set_up_system(d1, d2, little_m, big_m, spring_k1, spring_k2, b, x, x_dot, theta, theta_dot, px_len, scale, pivot, method, dt, font_size) without return types