You are correct on the first one, in that it is checking for the 2nd, Enter, or Clear key are pressed. However, the calculator processes it like this:
Lets say the key pressed is key 93
// Repeat max(K={21,105,45
First, Evaluate K={21,105,45
{0,0,0}
Take the Max of that list
0
Repeat continues while False
0 = False, according to Boolean logic
So, continue repeating
Now lets say the key pressed is key 105
// Repeat max(K={21,105,45
First, Evaluate K={21,105,45
{0,1,0}
Take the Max of that list
1
Repeat continues while False
1 = True, according to Boolean logic
So, stop repeating and move to the next section of code
You will sometimes also see
sum( used instead of max for detecting the key presses. It has the same function, just is a personal preference
The second one is a bit more complicated, but it is setting the upper and lower bounds for the motion. As you probably can guess, max( takes the maximum value of the inputs, and min( takes the minimum value of the inputs. This particular logic also makes use of Piecewise Expressions. So, if we break that piece of code down:
We need starting conditions, so lets assume O is 1 and K is 25;
This means the first option on the menu is selected, and we are trying to move up
//max(1,min(9,O+(K=34)-(K=25
The first thing evaluated is O+(K=34)-(K=25
1 + false - true
1 + 0 - 1
0
The next thing that gets evaluated is the min(9,{result}
min(9,0
0
Finally, the max is max(1,{result}
max(1,0
1
And then it returns; As you can probably see, it is impossible to go above the first option (1)
Now lets assume O is 9 and K is 34;
This means the last option on the menu is selected and we are trying to go down
//max(1,min(9,O+(K=34)-(K=25
The first thing evaluated is O+(K=34)-(K=25
9 + true - false
9 + 1 - 0
10
The next thing that gets evaluated is the min(9,{result}
min(9,10
9
Finally, the max is max(1,{result}
max(1,9
9
And then it returns; From this, it is impossible to go below the last option (9)
Using any other set of starting conditions, the expression will evaluate "normally"
Now lets assume O is 6 and K is 34;
This means we are on the 6th option and trying to go down
//max(1,min(9,O+(K=34)-(K=25
The first thing evaluated is O+(K=34)-(K=25
6 + true - false
6 + 1 - 0
7
The next thing that gets evaluated is the min(9,{result}
min(9,7
7
Finally, the max is max(1,{result}
max(1,7
7
And then it returns; Now the 7th option is selected
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