#
#  Plots comparing Reliability vs. Effort for Recovery Blocks and
#           N-Version Programming under different assumptions
#  Created for cs497LS Spring 1999
#  David Stott

set logscale y 
coverage = .95

set title "Probability of Failure (1 - R) vs. Effort"
set xlabel "Effort"
set ylabel "Prob. Fail (log plot)"

# reliability
        r(x) = (1-exp(-x/3))
# prob[failure]
        p(x) = 1-r(x)
# prob[fail] with 1/3 effort
        q(x) = exp(-x)


# rec block
 f(x) = (r(x))*(1-p(x)*p(x)*p(x)*coverage*coverage*coverage)/(1-p(x)*coverage)
# 3 version
 g(x) = 3*r(x)*r(x)*(1-r(x)) + r(x)*r(x)*r(x)
# 1 version
 h(x) = 1-q(x)
# rb 3 for the price of 1
 j(x) = (1 - q(x))*(1-q(x)*q(x)*q(x)*coverage*coverage*coverage)/(1-q(x)*coverage)

set term postscript

plot [0:20] 1-f(x) title "rec block(E)", 1-g(x) title "3-Version Prog.(E)", 1-h(x) title "Single Version(E/3)", 1-j(x) title "(3 for 1) Rec. Block(E/3)"