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PSU CMPSC200 MIDTERM 2024
QUESTIONS & CORRECT ANSWERS.
ALREADY GRADED A+.
.* - ANSElement-by-element array multiplication operator .^ - ANSElement-by-element array power operator
- ANSMatrix multiplication operator & - ANSAnd (used with vectors) && - ANSAnd (used with scalars) %c - ANSUsed for displaying just one character %e - ANSExponential notation %f - ANSFixed-point notation %g - ANSUsed for displaying the shorter of fixed-point notation or exponential notation %i - ANSinteger notation %s - ANSUsed for displaying a string of characters ^ - ANSMatrix power operator < - ANSLess than <= - ANSLess than or equal to == - ANSEquality check
- ANSGreater than = - ANSGreater than or equal to | - ANSOr (used with vectors) || - ANSOr (used with scalars) ~ - ANSNot
~= - ANSNot equal to 0 (zero) is the typical computer science representation for true, while 1 (one) is the typical computer science representation for false. - ANSFalse A matrix with a determinant that is non-zero - ANSA matrix for which an inverse does not exist A stiff equation is a differential equation where some numerical solution approaches are numerically stable unless you use extremely small step sizes. - ANSFalse alpha( ) - ANSUsed to adjust the transparency of a graphics object An array cannot contain multiple pieces of information. - ANSFalse animatedline( ) - ANSCreates a line animation Annotation axes - ANSEnables one to insert annotation objects such as lines, legends, and text boxes onto a figure Arithmetic and Logic Unit (ALU) - ANSPerforms mathematical operations Array - ANSContainer for multiple pieces of orderly information At the end of a for loop, the loop index variable keeps its most recent value. - ANSTrue axis( ) - ANSUsed to control the axes of a plot Bit - ANSOne 0 or 1 break - ANSUsed to cause the termination of the smallest enclosing for loop or while loop break and continue are "go-to" techniques that all programmers should readily use. - ANSFalse Built-in backslash operator approach for solving systems of linear equations - ANSsolution = A\b Byte - ANSEight 0 or 1's camlight( ) - ANSUsed to adjust lighting Cell array constructors - ANSCurly braces: { and }
cputime( ) - ANSReturns the total central processing unit time used by MATLAB Cross product - ANSResult is orthogonal to the plane defined by the two input vectors Cross product operation - ANSc = cross(a, b) cumtrapz( ) - ANSCalculates the cumulative sum using the trapezoidal method Curve fitting - ANSConstructs a line of best fit for a data set diff( ) - ANSUsed for creating finite differences diff( ) - ANSUsed to calculate symbolic derivatives disp( ) - ANSUsed for printing output to the screen, but does not generally have formatting capabilities dlmwrite( ) - ANSUsed to write delimited output Dot product operation - ANSc = dot(a, b) Double - ANSIs stored using 64 bits dsolve( ) - ANSUsed to solve symbolic differential equations Edit text box - ANSUsed for acquiring input from the user Effective strategies for improving the performance of MATLAB computer code include: - ANS1. Only printing using print statements
- Considering feedback from MATLAB itself
- Pre-allocating space for variables elseif (without a space) and else if (with a space) are generally not interchangeable. - ANSTrue etime( ) - ANSPerforms a comparison between a start time and an end time Every while loop can be made into a for loop, but not every for loop can be made into a while loop. - ANSFalse expand( ) - ANSMultiplies out all of the parts of the expression or equation Extrapolating beyond a given data set often results in excellent and useful results. - ANSFalse
Extrapolation - ANSConstructs estimated new data points beyond the range of a data set factor( ) - ANSFactors the expression false - ANSThe logical value 0 Field - ANSCan be thought of as a property fieldnames( ) - ANSAllows one to see the name of the fields figure( ) - ANSCalls a figure, creating it if necessary fimplicit( ) - ANSPlots implicit 2D plots Flowchart - ANSGrapgical representation of how code flows or progresses fmesh( ) - ANSPlots wireframe meshes fplot( ) - ANSPlots 2D plots fplot3( ) - ANSPlots 3D plots fprintf( ) - ANSUsed for printing output to the screen or to a file, and generally has formatting capabilities fsurf( ) - ANSPlots surface plots fzero( ) - ANSUsed for finding roots get( ) - ANSEnables one to acquire graphics object properties ginput( ) - ANSUsed to get data points from a plot gradient( ) - ANSUsed for creating finite differences Handle graphics - ANSThe components of the GUI are stored as properties relating to this idea horzcat( ) - ANSConcatenates horizontally How many counters can be used within a single program? - ANSAs many as the programmer would want or need imread( ) - ANSReads an image from a file
ln(x) - ANSNot a valid MATLAB command log(x) - ANSlog base e of x log10(x) - ANSlog base 10 of x loglog( ) - ANSPlots logarithm of y vs. logarithm of x Main Memory - ANSStores programs and program data into random access memory Mathematical function - ANSA mathematical relationship that maps an input to an output MATLAB array indexes must be positive integers. - ANSTrue MATLAB defaults to the behavior of hidden on unless hidden off is specified. - ANSTrue MATLAB function files are .m files like scripts are. - ANSTrue MATLAB generally interprets computer code line by line from the top to the bottom of a program. - ANSTrue MATLAB's desktop environment is an example of a GUI. - ANSTrue Matrix - ANS2D numeric array used in linear algebra with special mathematical properties Matrix inverse approach for solving systems of linear equations - ANSsolution = inv(A)*b Middle Riemann sum - ANSApproximates the function by its value at the middle point of the subinterval Most efficient approach computationally in MATLAB for solving systems of linear equations - ANSsolution = A\b nargin( ) - ANSDetermines the number of input arguments nargout( ) - ANSDetermines the number of output arguments Neglecting the possibility of else or elseif cases, a while loop can be thought of like a repetitious if statement. - ANSTrue Non-volatile Memory - ANSPermanant data storage num2str( ) - ANSConverts numbers to a character array
Numbers - ANSNumeric data numden( ) - ANSUsed to find the numerator and denominator of an expression Numerical differentation - ANSConstructs estimated derivative data for a data set Numerical differentiation tends to amplify the noise in one's data set. - ANSTrue ode113( ) - ANSA multi-step solver ode15i( ) - ANSUsed for solving implicit differential equations ode15s( ) - ANSGood for solving stiff differential equations and differential algebraic equations ode45( ) - ANSTypically your first choice solver unless you know something special about the ODE or ODE system One must use an even number of intervals when utilizing Simpson's rule. - ANSTrue orderfields( ) - ANSAllows one to reorder the fields Pass by reference - ANSA method for passing data to a function where memory address itself of a variable of interest is sent to the function Pass by value - ANSA method for passing data to a function where a copy of the value of a variable of interest is sent to the function Pass by value is not available in the MATLAB programming language, but pass by reference is. - ANSFalse pathtool - ANSUsed to instruct MATLAB to search for a given function pcolor( ) - ANSCreates a pseudocolor checkerboard plot plot( ) - ANSPlots y-data points vs. x-data points plot3( ) - ANSPlots a 3D plot polyfit( ) - ANSCreates a curve fit polyval( ) - ANSEvaluates the result of a polynomial from its coefficients pretty( ) - ANSPrints symbols in a plain-text format that resembles typeset mathematics
Some functions can have different behavior based on how they are used. - ANSTrue sprintf( ) - ANSUsed for printing output to a text string, and generally has formatting capabilities Static text box - ANSUsed for displaying text to the user String - ANSAn example of a character array Structure array - ANSThe MATLAB-created .m file uses this concept to pass information around the GUI-involved program Subfunctions - ANSThe MATLAB-created .m file uses this concept to organize the sections of the GUI-involved program subs( ) - ANSUsed to substitute in numbers, symbols, or other variable name(s) surf( ) - ANSPlots a 3D surface plot Switches can only check for equality, while if statements can check for equality or inequality. - ANSTrue syms - ANSDeclares a variable as a symbol The choice between numerical integration approaches depends on what the data looks like and what computational expense you can tolerate. - ANSTrue The default angular unit in MATLAB is radians unless specified otherwise. - ANSTrue The difference between for loops, while loop, and do while loops is that for loops ________, while loops _______, and do while loops _______, - ANS1. repeat a block of code a fixed number of times
- evaluate a condition before deciding if a block of code is to be run or repeated
- execute a block of code, then evaluate a condition to decide if the block of code should be repeated The dimensions of the result from a matrix multiplication operation are determined by the outer dimensions of the two matrices being multiplied. - ANSTrue The do while loop is a useful built-in feature of the MATLAB programming language. - ANSFalse The fact that a global variable is both visible and modifiable to all parts of a program is both an advantage and a disadvantage. - ANSTrue
The input (or output) order must be consistent between a function and whatever calls it.
- ANSTrue The input( ) command can be used to acquire numeric input from the user. The input( ) command can also be used to acquire character input from the user. - ANSTrue The key difference between animations and movies is that animations ______________ while movies ________________ - ANS1. are drawn live with no archiving
- enable archiving The key parts to every function are: - ANS1. The name of the function
- The outputs from the function, if applicable
- Comments that describe the other parts of the function
- The inputs to the function, if applicable The modern approach for symbolically solving ODEs in MATLAB is to use symbolic functions as an input into the built-in differential equation solver command. - ANSTrue The result of a matrix multiplication operation is mathematically defined if the inner dimensions of the two matrices being multiplied are not equal to each other. - ANSFalse The semi-colon at the end of a line of code is generally an optional piece of syntax in the MATLAB programming language. - ANSTrue There are sometimes multiple valid ways to solve the same programming tasks. - ANSTrue There are three primary steps for writing to a file with fprintf(). Which of the following are those steps? - ANS1. Write to the file
- Close the file
- Open the file, creating it if necessary tic and toc( ) - ANSUsed as a stopwatch feature title( ) - ANSAdds a title to a plot To use MATLAB's built-in numerical ODE solver, one must convert the ordinary differential equation or the system of ordinary differential equations into state-space form. For the purpose of this question, disregard the special case where one is numerically solving a single ODE that is first order. - ANSTrue Transposition (disregard the case of complex numbers) - ANSInterchanges the rows and columns
Which built-in command would you use if you wanted to generate uniformly distributed pseudorandom numbers? - ANSrand( ) Which of the following are characteristics of computers? - ANS1. Do not tire
- Follow instructions precisely
- Are reliable in most contexts Which of the following are characteristics of syntax errors? - ANS1. The code is written in such a way that MATLAB does not understand what it is being asked to do
- Results in a red error message displaying in the Command Window Which of the following are characters that require special formatting to be printed? - ANS1. Single quotation mark: '
- Percent sign: %
- Backslash:
Which of the following are important considerations when planning out a GUI-involved program? - ANS1. How to present the program to the user - What the program does
- How the program will look Which of the following are true about MATLAB variables? - ANS1. May contain letters or numbers
- Must begin with a letter
- May end with a letter Which of the following conditions are required for row echelon form? Row echelon form should not be confused with row reduced echelon form. - ANS1. The pivot of a nonzero row is always to the right of the pivot of the row above it
- All nonzero rows are above any rows that contain all zeros Which of the following is not true about plotting in MATLAB? - ANSPlotting is not a useful feature in the MATLAB programming language Which of the following purposes can a counter be used for? - ANS1. To keep track of "How many?"
- To keep track of "How much?" Which timing approach is most appropriate for measuring wall time, i.e. the amount of "real" time elapsed? - ANStic and toc( ) xor( ) - ANSExclusive or
