func_homo: Model derivative function
In HomoPolymer: Theoretical Model to Simulate Radical Polymerization

It supplies the derivatives of the model as requested by ode integrator in deSolve package

1	func_homo(t,y,pars,Kpf,Kdf,Kfz,Kfm,Kfs,Kfp,Kps,Kpss,KfCTA,KfCCTA,Ktf,Ktd,Ktc,roM,roS,roP)

`t`	integration time
`y`	actual value of the integrated variables
`pars`	vector of physical parameters
`Kpf`	function for propagation kinetic constant
`Kdf`	function for initiator decomposition kinetic constant
`Kfz`	function for inhibition kinetic constant
`Kfm`	function for transfer to monomer kinetic constant
`Kfs`	function for transfer to solvent kinetic constant
`Kfp`	function for transfer to polymer kinetic constant
`Kps`	function for external terminal bond kinetic constant
`Kpss`	function for internal terminal bond kinetic constant
`KfCTA`	function for transfer to agent kinetic constant
`KfCCTA`	function for transfer to catalytic agent kinetic constant
`Ktf`	function for bimolecular termination kinetic constant
`Ktd`	function for disproportion kinetic constant
`Ktc`	function for combination kinetic constant
`roM`	function for density of Monomer
`roS`	function for density of Solvent
`roP`	function for density of Polymer