v0 = 5
g = 9.81
t = 0.6
y = v0*t - 0.5*g*t**2
print y

C = 21; F = (9.0/5)*C + 32; print F

C = raw_input('C=? ')   # C becomes a string
C = float(C)            # convert to float so we can compute
F = (9./5)*C + 32
print F

n = int(raw_input('n=? '))

for i in range(2, 2*n+1, 2):
    print i

# or:
print range(2, 2*n+1, 2)

# or:
for i in range(1, n+1):
    print 2*i

C = 21; F = (9.0/5)*C + 32; print F

# Need to fill in sys.argv for use in the notebook
import sys
sys.argv[1] = '21'

import sys
C = float(sys.argv[1])   # read 1st command-line argument
F = 9.0*C/5 + 32
print F

s = '1+2'
r = eval(s)
r

type(r)

r = eval('[1, 6, 7.5] + [1, 2]')
r

type(r)

r = eval('math programming')

r = math programming

s = "'math programming'"
r = eval(s)
r

i1 = eval(raw_input('Give input: '))
i2 = eval(raw_input('Give input: '))
r = i1 + i2
print '%s + %s becomes %s\nwith value %s' % \
      (type(i1), type(i2), type(r), r)

statement = 'r = 1+1'   # store statement in a string
exec(statement)
print r                 # prints 2

somecode = '''
def f(t):
    term1 = exp(-a*t)*sin(w1*x)
    term2 = 2*sin(w2*x)
    return term1 + term2
'''
exec(somecode)  # execute the string as Python code

formula = raw_input('Write a formula involving x: ')
code = """
def f(x):
    return %s
""" % formula
from math import *  # make sure we have sin, cos, log, etc
exec(code)          # turn string formula into live function

# Ask the user for x values and evaluate f(x)
x = 0
while x is not None:
    x = eval(raw_input('Give x (None to quit): '))
    if x is not None:
        y = f(x)
        print 'f(%g)=%g' % (x, y)

from scitools.std import StringFunction
formula = 'exp(x)*sin(x)'
f = StringFunction(formula)
f(0)

from math import pi
f(pi)

print str(f)

g = StringFunction('A*exp(-a*t)*sin(omega*x)',
    independent_variable='t', A=1, a=0.1, omega=pi, x=5)
print g(1.2)
g.set_parameters(A=2, x=10)
print g(1.2)

from Tkinter import *
root = Tk()
C_entry = Entry(root, width=4)
C_entry.pack(side='left')
Cunit_label = Label(root, text='Celsius')
Cunit_label.pack(side='left')

def compute():
    C = float(C_entry.get())
    F = (9./5)*C + 32
    F_label.configure(text='%g' % F)

compute = Button(root, text=' is ', command=compute)
compute.pack(side='left', padx=4)

F_label = Label(root, width=4)
F_label.pack(side='left')
Funit_label = Label(root, text='Fahrenheit')
Funit_label.pack(side='left')

root.mainloop()

f = open('data.txt', 'w')
f.write("""21.8
18.1
19
23
26
17.8
""")
f.close()

infile = open('data.txt', 'r')    # open file
mean = 0
for line in infile:
    number = float(line)          # line is string
    mean = mean + number
    print 'number=%g' % g
mean = mean/len(lines)
print mean

f = open('tmp.txt', 'w')
f.write("""Line 1.
Line 2.
Line 3.
Line 4.
""")
f.close()

infile = open('tmp.txt', 'r')
lines = infile.readlines()  # read all lines
lines

infile.readline()  # no more to read

infile = open('tmp.txt', 'r')
infile.readline()    # read one line

infile.readline()    # read next line

for line in infile:  # read the next lines to the end
    print line

infile = open('tmp.txt', 'r')
filestr = infile.read()
filestr

filestr.split()  # split out all words

line = 'Line 3.\n'
line.split()

line.split('e')

f = open('rainfall.txt', 'w')
f.write("""Average rainfall (in mm) in Rome: 1188 months between 1782 and 1970
Jan  81.2
Feb  63.2
Mar  70.3
Apr  55.7
May  53.0
Jun  36.4
Jul  17.5
Aug  27.5
Sep  60.9
Oct  117.7
Nov  111.0
Dec  97.9
Year 792.9
""")
f.close()

line = 'Oct  117.7'
words = line.split()
words

type(words[1])   # string, not a number!

def extract_data(filename):
    infile = open(filename, 'r')
    infile.readline() # skip the first line
    months = []
    rainfall = []
    for line in infile:
        words = line.split()
        # words[0]: month, words[1]: rainfall
        months.append(words[0])
        rainfall.append(float(words[1]))
    infile.close()
    months = months[:-1]      # Drop the "Year" entry
    annual_avg = rainfall[-1] # Store the annual average
    rainfall = rainfall[:-1]  # Redefine to contain monthly data
    return months, rainfall, annual_avg

months, values, avg = extract_data('rainfall.dat')
print 'The average rainfall for the months:'
for month, value in zip(months, values):
    print month, value
print 'The average rainfall for the year:', avg

data = \
[[ 0.75,        0.29619813, -0.29619813, -0.75      ],
 [ 0.29619813,  0.11697778, -0.11697778, -0.29619813],
 [-0.29619813, -0.11697778,  0.11697778,  0.29619813],
 [-0.75,       -0.29619813,  0.29619813,  0.75      ]]

outfile = open('tmp_table.dat', 'w')
for row in data:
    for column in row:
        outfile.write('%14.8f' % column)
    outfile.write('\n')
outfile.close()

from math import log
r = log(6)   # call log function in math module

import sys
x = eval(sys.argv[1])  # access list argv in sys module

from math import log as ln

def present_amount(A0, p, n):
    return A0*(1 + p/(360.0*100))**n

def initial_amount(A, p, n):
    return A*(1 + p/(360.0*100))**(-n)

def days(A0, A, p):
    return ln(A/A0)/ln(1 + p/(360.0*100))

def annual_rate(A0, A, n):
    return 360*100*((A/A0)**(1.0/n) - 1)

with open('interst.py', 'w') as outfile:
    outfile.write("""
from math import log as ln

def present_amount(A0, p, n):
    return A0*(1 + p/(360.0*100))**n

def initial_amount(A, p, n):
    return A*(1 + p/(360.0*100))**(-n)

def days(A0, A, p):
    return ln(A/A0)/ln(1 + p/(360.0*100))

def annual_rate(A0, A, n):
    return 360*100*((A/A0)**(1.0/n) - 1)
""")

# How long time does it take to double an amount of money?

from interest import days
A0 = 1; A = 2; p = 5
n = days(A0, 2, p)
years = n/365.0
print 'Money has doubled after %.1f years' % years

if __name__ == '__main__':
    A = 2.2133983053266699
    A0 = 2.0
    p = 5
    n = 730
    print 'A=%g (%g) A0=%g (%.1f) n=%d (%d) p=%g (%.1f)' % \
          (present_amount(A0, p, n), A,
           initial_amount(A, p, n), A0,
           days(A0, A, p), n,
           annual_rate(A0, A, n), p)

def test_all_functions():
    # Define compatible values
    A = 2.2133983053266699; A0 = 2.0; p = 5; n = 730
    # Given three of these, compute the remaining one
    # and compare with the correct value (in parenthesis)
    A_computed = present_amount(A0, p, n)
    A0_computed = initial_amount(A, p, n)
    n_computed = days(A0, A, p)
    p_computed = annual_rate(A0, A, n)
    def float_eq(a, b, tolerance=1E-12):
        """Return True if a == b within the tolerance."""
        return abs(a - b) < tolerance

    success = float_eq(A_computed,  A)  and \
              float_eq(A0_computed, A0) and \
              float_eq(p_computed,  p)  and \
              float_eq(n_computed,  n)
    assert success  # could add message here if desired

if __name__ == '__main__':
    test_all_functions()

x = 20
r = eval('x + 1.1')
r

type(r)

def f(x):
    return 2*x - 3   # one root x=1.5

eps = 1E-5
a, b = 0, 10

fa = f(a)
if fa*f(b) > 0:
    print 'f(x) does not change sign in [%g,%g].' % (a, b)
    sys.exit(1)

i = 0   # iteration counter
while b-a > eps:
    i += 1
    m = (a + b)/2.0
    fm = f(m)
    if fa*fm <= 0:
        b = m  # root is in left half of [a,b]
    else:
        a = m  # root is in right half of [a,b]
        fa = fm
x = m          # this is the approximate root

def bisection(f, a, b, eps):
    fa = f(a)
    if fa*f(b) > 0:
        return None, 0
        # Alternative: raise ValueError(
        # 'No change of sign in [%g,%g]' % (a, b))

    i = 0   # iteration counter
    while b-a > eps:
        i += 1
        m = (a + b)/2.0
        fm = f(m)
        if fa*fm <= 0:
            b = m   # root is in left  half of [a,b]
        else:
            a = m   # root is in right half of [a,b]
            fa = fm
    return m, i

print bisection(f=lambda x: 2*x-3, a=0, b=10, eps=1E-5)

def test_bisection():
    def f(x):
        return 2*x - 3   # only one root x=1.5

    eps = 1E-5
    x, iter = bisection(f, a=0, b=10, eps=eps)
    success = abs(x - 1.5) < eps  # test within eps tolerance
    assert success, 'found x=%g != 1.5' % x

if __name__ == '__main__':
    test_bisection()