2017-09-11-131636.ipynb

Kernel: Python 3 (Anaconda)

x1=2.
x2=3.
s=x1+x2
print('s', s)

s 5.0

import math
x=4.
a=math.sqrt(x)
print('a',a)

a 2.0

import matplotlib.pyplot as plt
plt.figure(figsize=(6,4))
plt.plot([1,2,3,4,5],[1,4,9,16,25], marker='o', color='r')
plt.xlabel('x')
plt.ylabel('y')
plt.grid(1)
plt.minorticks_on()
plt.title('grafik $y=x^2$')
plt.show()

import numpy as np
A=np.array([[-2.,1.,0.],[1.,-2.,1.],[0.,1.,-2.]])
print(A)

[[-2.  1.  0.]
 [ 1. -2.  1.]
 [ 0.  1. -2.]]

X=[1,2,3,4,5]
Y=[x**2 for x in X]
print(Y)

[1, 4, 9, 16, 25]

def power(x,p=2):
    return x**p
print(power(2))

4

X=['a','b','c','d']
print(X[0], X[3])
print(X[-1], X[-2])
print(X[1:-1])

a d
d c
['b', 'c']

c={'r':100, 'g':20, 'b':30}
print(c['r'])

100

c={'v':100, 'a':20, 'n':30}
print(c['v'],c['a'],c['n'])

100 20 30

c={'v':10, 'a':100, 'n':1000}
print(c['v'],c['a'],c['n'])

10 100 1000

del c['v']
print(c)

{'a': 100, 'n': 1000}

#help(dict)
T=('a','b','c',)
T0=()
T1=('a',)
print(T[:-1])

('a', 'b')

class Point: #(object):
    #
    def _init_(self,x,y):
        self.x=x
        self.y=y
        #
        def _str_(self):
            return "Point(x={} y={})".format(self.x, self.y)

print(Point)
pt = Point(1., 2.)
print(pt.x, pt.y)
print(pt)

<class '__main__.Point'>

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-19-5d36f4df8c5c> in <module>()
      1 print(Point)
----> 2 pt = Point(1., 2.)
      3 print(pt.x, pt.y)
      4 print(pt)
TypeError: object() takes no parameters

import math
class Vector(Point):
    #
    def norma(self):
        return math.sqrt(self.x**2+self.y**2)
    #
    def_str_(self):
        return "Vector({}, {})".format(self.x, self.y)

  File "<ipython-input-21-da5ee71ec13f>", line 7
    def_str_(self):
                  ^
SyntaxError: invalid syntax

a=0
l=[1,2,3,4,5,-3,-2,0]
for x in l:
    if x>0:
        a=a+x
print(a)

15

def count_positives(m):
    a=0
    for x in m:
        if x>0:
            a=a+1
    return a
l=[1,2,3,4,5,-3,-2,0]
print(count_positives(l))

5

s = 0
x=0.5
fact=1
for i in range(1, 21):
   fact = fact*i
   s=s+(((-1)**i)/(fact)*(x**i))
print(s)

-0.3934693402873664