class_docstr: Meyer [1]_ objective function.
  
  ..[1] https://www.itl.nist.gov/div898/strd/nls/data/mgh10.shtml
  
  TODO NIST regression standard
class_docstr_tok: ["Meyer","[","1","]","_","objective","function",".","..","[","1","]","https",":","\/\/www.itl.nist.gov\/div898\/strd\/nls\/data\/mgh10.shtml","TODO","NIST","regression","standard"]
code: def fun(self, x, *args):
      self.nfev += 1
  
      vec = x[0] * exp(x[1] / (self.b + x[2]))
      return sum((self.a - vec) ** 2)
  
imports: from numpy import abs, asarray, cos, exp, log, arange, pi, prod, sin, sqrt, sum, tan
  from .go_benchmark import Benchmark, safe_import
label_desc: Use image node_id 2 for calling the Meyer obj's underlying member method code with example usage: obj.fun(x) and returns: sum