import openturns as ot
from openturns.viewer import View

f1 = ot.SymbolicFunction(["x"], ["sin(x)"])
f2 = ot.SymbolicFunction(["x"], ["x"])
f3 = ot.SymbolicFunction(["x"], ["cos(x)"])

f = ot.LinearCombinationFunction([f1, f2, f3], [1.0, 2.0, 3.0])
graph = f.draw(0.0, 10.0)
graph.setTitle("y=1*f1+2*f2+3*f3")
View(graph, figure_kw={"figsize": (8, 4)}, add_legend=True)