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Python: Functions Functions Mathematical functions f(x) = x 2 - - PowerPoint PPT Presentation
Python: Functions Functions Mathematical functions f(x) = x 2 - - PowerPoint PPT Presentation
Python: Functions Functions Mathematical functions f(x) = x 2 f(x,y) = x 2 + y 2 In programming functions also help creating better structure with decomposition Functions
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Functions
Source:https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-0001-introduction-to-computer-science-and- programming-in-python-fall-2016/lecture-slides-code/
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Defining and invoking a function
Source:https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-0001-introduction-to-computer-science-and- programming-in-python-fall-2016/lecture-slides-code/
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Defining and invoking a function
Source:https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-0001-introduction-to-computer-science-and- programming-in-python-fall-2016/lecture-slides-code/
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Defining and invoking a function
Consider f(x) = x2 def square(x):
#defining function
return x*x
square(4) #invoking function 16 # output
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Defining and invoking a function
Example: Functions may not have arguments, and return statement def myprint():
#defining function
print (“Hello world”)
myprint() #invoking function Hello world # output
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Defining and invoking a function
Example: Function calling another function def repeatmyprint():
myprint() myprint() repeatmyprint() #invoking function Hello world # output Hello world
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Scope of a Variable
Source:https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-0001-introduction-to-computer-science-and- programming-in-python-fall-2016/lecture-slides-code/
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Scope of a Variable
Source:https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-0001-introduction-to-computer-science-and- programming-in-python-fall-2016/lecture-slides-code/
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Scope of a Variable
Source:https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-0001-introduction-to-computer-science-and- programming-in-python-fall-2016/lecture-slides-code/
returns 4
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Scope of a Variable
Source:https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-0001-introduction-to-computer-science-and- programming-in-python-fall-2016/lecture-slides-code/
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Function: Arguments
Source:https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-0001-introduction-to-computer-science-and- programming-in-python-fall-2016/lecture-slides-code/
No argument One argument One argument (function) ( ) ( ) ( )
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Function: Arguments
Source:https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-0001-introduction-to-computer-science-and- programming-in-python-fall-2016/lecture-slides-code/
( ) ( ) ( ) ( ) ( ) ( )
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Function: Arguments
Source:https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-0001-introduction-to-computer-science-and- programming-in-python-fall-2016/lecture-slides-code/
( ) ( ) ( ) ( ) ( ) ( )
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Function: Arguments
Source:https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-0001-introduction-to-computer-science-and- programming-in-python-fall-2016/lecture-slides-code/
( ) ( ) ( ) ( ) ( ) ( )
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Function: Arguments
Source:https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-0001-introduction-to-computer-science-and- programming-in-python-fall-2016/lecture-slides-code/
Output
inside func_a None ( ) ( ) ( ) ( ) ( ) ( )
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Function: Arguments
Source:https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-0001-introduction-to-computer-science-and- programming-in-python-fall-2016/lecture-slides-code/
Output
inside func_b 7 ( ) ( ) ( ) ( ) ( ) ( )
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Function: Arguments
Source:https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-0001-introduction-to-computer-science-and- programming-in-python-fall-2016/lecture-slides-code/
Output
inside func_c inside func_a None ( ) ( ) ( ) ( ) ( ) ( )
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Function: Scope
Source:https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-0001-introduction-to-computer-science-and- programming-in-python-fall-2016/lecture-slides-code/
x is redefined locally
2 5
Output
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Function: Scope
Source:https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-0001-introduction-to-computer-science-and- programming-in-python-fall-2016/lecture-slides-code/
Can access x defined outside Output
5 6 5
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Function: Scope
Source:https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-0001-introduction-to-computer-science-and- programming-in-python-fall-2016/lecture-slides-code/
Can not modify x defined outside UnboundLocalError Output
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Function: Scope (Example)
Source:https://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-0001-introduction-to-computer-science-and- programming-in-python-fall-2016/lecture-slides-code/