What is gray coding?

In the genetic toolbox of matlab, there is a function which is called bs2rv which takes random binary strings and map them to real numbers using either binary or gray coding.

I don't understand how bs2rv works, what exactly happens. I want to understand the algorithm of it, can someone help me understand it?

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Purpose

binary string to real value conversion

Synopsis

Phen = bs2rv(Chrom, FieldD)

Description

Chrom=crtbp(Nind,Nvar) where crtbp generates a random matrix of element zero and one of size Nind rows and Nvar columns

Phen = bs2rv(Chrom, FieldD) decodes the binary representation of the

population, Chrom, into vectors of reals. The chromosomes are seen as

concatenated binary strings of given length, and decoded into real numbers over a

specified interval using either standard binary or Gray coding according to the

decoding matrix, FieldD. The resulting matrix, Phen, contains the

corresponding population phenotypes.

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The matrix FieldD has the following structure:

The rows of the matrix are composed as follows:

len, a row vector containing the length of each substring in Chrom. Note that

sum(len) should equal length(Chrom).

lb and ub are row vectors containing the lower and upper bounds respectively for

each variable used.

code is a binary row vector indicating how each substring is decoded. Select

code(i) = 0 for standard binary and code(i) = 1 for Gray coding.

[Image Analyst]

Did you look at the definition in Wikipedia?