Performs an polynomial mutation as used in the SMS-EMOA algorithm. Polynomial mutation tries to simulate the distribution of the offspring of binary-encoded bit flip mutations based on real-valued decision variables. Polynomial mutation favors offspring nearer to the parent.
mutPolynomial(ind, p = 0.2, eta = 10, lower, upper)[numeric]
[numeric]
Numeric vector / individual to mutate.
[numeric(1)]
Probability of mutation for each gene of an offspring. In other words, 
the probability that the value (allele) of a given gene will change.
Default is 0.2
[numeric(1)
Distance parameter to control the shape of the mutation distribution. 
Larger values generate offspring closer to the parents.
Default is 10.
[numeric]
Vector of minimal values for each parameter of the decision space.
Must have the same length as ind.
[numeric]
Vector of maximal values for each parameter of the decision space.
Must have the same length as ind.
[1] Deb, Kalyanmoy & Goyal, Mayank. (1999). A Combined Genetic Adaptive Search (GeneAS) for Engineering Design. Computer Science and Informatics. 26. Retrieved from http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.27.767&rep=rep1&type=pdf
Other mutators: 
mutBitflip(),
mutGauss(),
mutInsertion(),
mutInversion(),
mutJump(),
mutScramble(),
mutSwap(),
mutUniform()