54 decision making
Exercise 7: Decision making
Write your own script files to solve the following problems:- Write a script file that asks the user for the input of a number and
returns the natural logarithm of the number if the number is positive,
and displays an error message otherwise. - The cost per kilometre for a rental car is £0.50 for the first 100 kilometres,
£0.30 for the next 200 kilometres and £0.20 for all kilometres in excess
of 300 kilometres. Write a function that determines the total cost for a
given number of kilometres. - Write a function to evaluatef(x,y)for any two user specified valuesx
andy. The functionf(x,y)is defined as:
f(x,y) =
x+y x> 0 andy> 0
x+y^2 x> 0 andy < 0
x^2 +y x < 0andy> 0
x^2 +y^2 x < 0andy < 0- The energy loss due to fluid flow through a pipe can be calculated using
the following equations:
hL=f(
L
D
)(
V^2
2
)
, V=
Q
A, A=
πD^2
4 , Re=DVρ
μ ,where:hL=energy loss per mass of fluid flowing (J/kg)
f=friction factor (dimensionless)
L=pipe length (m)
D=pipe diameter (m)
V=average fluid velocity (m/s)
Q=volumetric flow rate (m^3 /s)
A=pipe cross-sectional area (m^2 )
Re=Reynolds number (dimensionless)
ρ=fluid density (kg/m^3 )
μ=fluid viscosity (kg/ms)