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ENGINEERING 1D04 Tutorial 1 WELCOME! What we’re doing today • Who am I • How to do well • What are computer programs • Software Development Cycle • Pseudo Code vs. Code • Variables • Getting Input from a User • Python as a Calculator • Expressions/Literals • Comments • Print Statement • For loop/range function • Practice! Important Info! Who am I? • Rachel Lim • Just completed third year of Electrical and Biomedical Eng • Have TAd for five terms so far, this is my sixth • Love to travel • Email: [email protected] How to Succeed • Practice, practice, practice! • Attend lectures, tutorials and labs • Practice before major labs WHAT IS A COMPUTER PROGRAM? Think “Recipe” Software Development Process Analyze the Problem Maintenance Determine Specifications Test/Debug Create a Design Implement the Design Coding • Pseudo Code • • • • • • Step 1: Gather Ingredients Step 2: Preheat Oven to 350 F Step 3: Mix Dry Ingredients Step 4: Mix Wet Ingredients Step 5: Combine Wet and Dry Step 6: Bake for 20 minutes • Actual Code • • • • • • oven = 350 wet = “milk” + “eggs” dry = “flour + “sugar” mix = wet+dry cookies = string(oven) + mix print cookies Variables/Elements • A name for a space to hold information • The names are case sensitive • Should have some context • Names are called identifiers or variables • Must begin with a letter or underscore Variables Names • Good • • • • • • X Temp Count Velocity Speed height • Bad • • • • xhgjeo !jigjrejgi A,b,c,d,e,f,g (using letters as all of your variable names can become confusing) for, in, print (reserved words for python – already have another function) Variable Types • int: plain integers > 3 • long: long integers >3L • double: floating point numbers >3.0 • complex: real and imaginary part numbers >3+4i • string: sequence of characters > hello • bool: Boolean (True or False) • type() will tell you what type of variable it is Built in Functions • abs() : gives you the absolute value of a number • abs(-3) = 3 • round() : rounds a floating-point number to the nearest integer • round(1.2) = 1 • int() and float() and string() will change what’s in brackets to its own type • int(1.2) = 1, float(1) = 1.0, string(1) = “1” Assigning Variables • Correct format: • X=3 • So the variable name will be on the LHS with the assigned value on the RHS after an equal sign • You can also assign two values to two variables in one line: • x,y = 3,4 • How would you swap two values? • x,y = y,x Getting input from a user • Say we would like to ask the user for a number • We can use the function “input” • Ex. x= input(“please enter a number: ”) Using Python as a Calculator • + • - • / • % • * • ** Remember BEDMAS applies! Integer Division • When you divide two integers, the answer can be given as a quotient and a remainder • • When Python divides, only the quotient will be given as the answer • • Ex. 26/10 quotient: 2 remainder: 6 Ex. 26/10 = 2 This is known as Integer Division How do we avoid this? • Make sure both numbers aren’t integers: 26., 26.0 and/or 10., 10.0 • Ex. What will the result be if we type in 95/100? Expressions and Literals • Expressions: something that produces or calculates a new value • ie. x=3+5 • Literal: something that represents a specific value • ie. 3 Comments • Every time you code you should leave comments! • Comments help other people understand your code • In Python, comments begin with a # • This means that Python will ignore anything coming after this symbol Print • We use print to output values onto the screen • Successive print statements will print on different lines • Blank print statements will print blank lines • You can use a comma to print multiple values on the same line Definite Loop and Range Function • A loop that will run for a specified number of times • Takes the format for <var> in <sequence>: <Body> • Range is a function that will return a list of numbers • REMEMBER! It always starts at zero What will each do? • Python Demo • Range(6) • Range(1,6) • Range(4,-1) • Range(1,5,2) Practice • Quadratic Formula • • Solve: x2-x+6=0 And print it Practice for Major 1 • A torus is a donut-shaped solid made by forming a tube into a circle. The surface area A of a torus with circle radius R and tube radius r is given by the following formula: • • A= 4∏2Rr Requirements: • Program asks user to enter circle radius R and tube radius r, in that order Program computes A and B, surface area of torus with R and 3r • Program outputs A, B and C where C = 100| • 𝐴−𝐵 | in this order with appropriate labels 𝐵
