How to make a square root fit to data in Julia 1.0

Question

I have a very simple question. How would one fit a square root model to a dataset in Julia. I'm currently using the GLM package, which works very well with linear data. I need to plot a phase velocity as a function of string tension, and it seems like @formula(v ~ sqrt(T)) does not work in

import GLM, DataFrames # No global namespace imports
df = DataFrames.DataFrame(
  v = [1, 1.5, 1.75],
  T = [1, 2, 3]
)
fit = GLM.glm(GLM.@formula(v ~ T^(1/2)), vs)

Is GLM at all viable here, or do I need to resort to another package such as LsqFit?

Answer 1

You can use sqrt in your model formula. Just do it e.g. like this:

GLM.lm(GLM.@formula(v ~ sqrt(T)), df)

if you want to fit a linear model use lm function and a second argument should be a data frame, which is df in your case.