get_residual: Residuals for the Gompertz Curve
In davidmaciel/covertzbr: Gompertz Curve for the COVID-19 epidemic in Brazil

Calculate the sum of squared residuals for a gompertz curve, given a vector of observed total deaths.

1	get_residual(time, obs, lambda, mu, a)

`time`	Integer. A vector of one or more values, counted as the number of days.
`obs`	Numeric. A vector of obseverd total deaths. It must be of the same length as `time`
`lambda`	Numeric. A single value for the lambda parameter in the gompertz equation.
`mu`	Numeric. A single value for the mu parameter in the gompertz equation.
`a`	Numeric. A single value for de alpha parameter in the gompertz equation.