Help figuring out this Function file

This isnt HW, its a review for my final exam. I thought I had figured it out until I put in my own values and that just threw away my theory. Help please

• function [ y ] = mysum2( x,a,b )
• sum=0;
• for k=1:length(x)
• if a<=x(k)<=b
• sum = sum+x(k);
• end
• end
• y=sum;
• end

plug in array b b=[4 14 6 3 4 10 8 6]

y=mysum(b,-5,0) y=0

y=mysum(b,1,3) y=55

y=mysum(b,6,7) y=55

y=mysum(b,60,70) y=55

plug in array c=[3 -2 4 4 5 1 -4 -2 7] y=mysum(c,-10,-6) y=0

y=mysum(c,-2,0) y=-4

y=mysum(c,-2,-2) y=16

y=mysum(c,6,7) y=16

Answer 1

[James Tursa]

Your test should be:

if a<=x(k) && x(k)<=b

Your original line is interpreted as follows:

if (a<=x(k))<=b

The first test gives a logical result, which is going to work out to be 1 <= b or 0 <= b depending on the logical result of the first a <= x(k). This is of course not what you intended.