NCL Website header
NCL Home > Documentation > Functions > General applied math

log

Computes the natural log of a numeric type.

Prototype

	function log (
		value  : numeric   
	)

	return_val [dimsizes(value)] :  float or double

Arguments

value

An array of one or more values of any dimension value > 0.0

Return value

Returns a floating point array dimensioned the same as value.

The return type is floating point if the input is floating point, and double if the input is of type double.

Description

This function returns the natural logarithm of each element of value. Missing values are ignored.

See Also

exp log10

Examples

Example 1

  f = 3.6
  log_f = log(f)
  print(log_f)        ; Should be 1.280934
Example 2: Find the cube root of 3112.136 [=x^3]

  x = exp( log(3112.136)/3.0 )
  print( x )        ; Should be 14.6
Example 3: Solve the following for x: y = 9.328*(0.729-x^3) - 1.8

   y = 2.0
   x = exp( log(0.729-((y+1.8)/9.328))/3.0 )  ; = 0.685

Errors

If value < 0.0, nan is returned.

If value = 0.0, -inf is returned.