natural_log

Description

of math_mods
==============================
The complex_math module performs binary math operations on 2-vector
fields that represent complex numbers.  The first vector component
represents the real part of the complex number.  The second vector
component represents the imaginary part of the complex number.
Exponential computes 'e' raised to each field value.
Natural_log computes log base e of a real field.
Reasons for making math_mods
==================================
Had some uses for them when doing image/volume processing.
Compiling math_mods
=========================
Math_mods was developed on the Convex platform.  However, the code
can easily be compiled on other platforms if needed.  You will need to
remove the #pragma directives from the source code, and modify the
Makefile for the C compiler on the given platform.  NO specific Convex
routines are called in luminence.
Enjoy :-)
----------

Author

    Earl Hood
    Advanced Scientific Computing: OAC
    University of California: Irvine
    Irvine, CA  92717
    ehood@uci.edu
                                                                  Natural Log
                                                Compute log base e of a field

Summary

   Name        natural log

Type

      filter

Inputs

     field any-dimension n-vector real any-coordinates

Outputs

    field any-dimension n-vector real any-coordinates

Parameters

 None
Description
            Natural Log computes log base e of a real field:
                newvalue = log (value)
                              e
Inputs
            Data field (required; field any-dimension n-vector real 
                        any-coordinates)
Outputs
            Data Field (field any-dimension n-vector real any-coordinates)

Notes

            Logorithmic functions are not defined for values less than or
            equal to zero.  If the input field has a value less than or equal
            to zero, NATURAL LOG will use 1.0e-30 as the natural log of that
            value.  The Statistics module can be used to check if the input
            field has negative or zero values.

Example

                                READ FIELD
                                     |
                              FIELD TO FLOAT
                                     |
                                NATURAL LOG
                                     | 
                                PRINT FIELD

Related modules

            field to float, statistics, exponential