computeIC50 function gives unexpected result

[cscheeder]

The computeIC50 function gives unexpected results as it returns a fixed concentration value that matches one of the input concentrations (i.e. experimental conditions). Also the results from computeIC50 and computeICn with n = 50 differ.

concentrations <- rev(1/2^seq(0,8) * 1)
viabilities <-  c(99.2, 98.4, 96.9, 93.9, 88.2, 77.8, 60, 33.3, 0)

print(PharmacoGx::computeIC50(concentration = concentrations, viability = viabilities))
print(PharmacoGx::computeICn(concentration = concentrations, viability = viabilities,n=50))

this seems to give the expected result:
print(PharmacoGx::computeICn(concentration = concentrations, viability = viabilities,n=0.5))

sessionInfo()