# cf.Variable.cos

`Variable.``cos`(bounds=True, i=False)

  Take the trigonometric cosine of the data array.

  Units are accounted for in the calculation, so that the the cosine of 90 degrees_east is 0.0, as is the cosine of 1.57079632 radians. If the units are not equivalent to radians (such as Kelvin) then they are treated as if they were radians.

  The output units are ‘1’ (nondimensionsal).

  See also

  `sin`, `tan`

  Examples 1: |

      >>> g = f.cos()

  Parameters: | bounds: optional Ignored. i: `bool`, optional If True then update the variable in place. By default a new variable is created. In either case, a variable is returned.
  Returns: | out: `cf.Variable` The variable with the cosine of data array values.
  Examples 2: |

      >>> f.Units
      <CF Units: degrees_east>
      >>> print f.array
      [[-90 0 90 --]]
      >>> f.cos()
      >>> f.Units
      <CF Units: 1>
      >>> print f.array
      [[0.0 1.0 0.0 --]]

      >>> f.Units
      <CF Units: m s-1>
      >>> print f.array
      [[1 2 3 --]]
      >>> f.cos()
      >>> f.Units
      <CF Units: 1>
      >>> print f.array
      [[0.540302305868 -0.416146836547 -0.9899924966 --]]