Fig. 3.

Histogram of residuals for general regression neural network-fruit fly optimization algorithm (GRNN-FOA) models developed for forecasting dry weight, intracellular (µg g⁻¹DW), intracellular (µg l⁻¹), extracellular and total yield of paclitaxel and extracellular paclitaxel portion in Corylus avellana cell cultures treated with fungal elicitors