SUNY Geneseo Department of Computer Science

“For” Loops, Day 3

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Misc

Exam 1 ready to return

• Average = 33, median = 34
• Writing functions in Matlab
  • function to compute 3x - 2y

            function z = f( x , y )
                z = 3 * x - 2 * y;
            end
            
            >> f( 4, 8 )
            >> 10 * f( 3, 9)

Questions?

Nested loops?

• Whole loops can be done over and over by other loops, just as any statement can

        x = 0;
        for i = 1 : 10
            x = x + i;
            for j = 1 : 20
                y = i + j;
            end
            fprintf( '%d\n', i );
        end

Concrete example in Matlab: compute the sum of all the values in a matrix

A = [ 2 5 3; 9 4 10 ]
A =
    2     5     3
    9     4    10
sum = 0;
for r = 1 : 2
    for c = 1 : 3
        sum = sum + A(r,c)
    end
end
sum =
    2
sum =
    7
sum =
    10
sum =
    19
sum =
    23
sum =
    33
sum
sum =
    33

Edge and special cases for Riemann sums?

• a = b
• f(x) = 0, f(x) = 1 (if you're doing the version that takes the function to integrate as a parameter)

For Loops Lesson

Next

“While” loops

Read / watch

• Attaway section 5.3
• “While Loops” from Edinburgh

Handout