SUNY Geneseo Department of Mathematics

“For” Loops

Monday, October 20

Math 230 01
Fall 2014
Prof. Doug Baldwin

Misc
- Mac OS X upgrades aren’t getting along with Matlab
Questions?
For Loops
- Sections 5.1 and 5.2
  - Basic idea of loop to run statements some known number of times
  - Nested loops: can have loops inside loops
  - Common uses: running sums
Function Handles
- “Handle” = value that can be stored in a variable and provides access to the internal representation of something (in this case, a function)
- f(....) calls (i.e., runs) function
- f is function name, can’t do much with it by itself
- @f produces a handle to function
```
>> x = sqrt(4)
x =
    2
>> y = sqrt
Error using sqrt
Not enough input arguments.
>> z = @sqrt
z = 
    @sqrt
```
- Can use handle as if it were a function. Handles are particularly nice for passing functions to other functions.
```
>> z(9)
ans =
    3
>> riemann2( @sqrt, 0, 10, 100 )
ans =
   20.9173
>> r = @riemann2
r = 
    @riemann2
```
- Also use handles to create unnamed functions on-the-fly when you need them
```
>> @(x)x^4
ans = 
    @(x)x^4
>> ans(8)
ans =
    4096
```
Numerical Integration Lab
- Programming strategy: work on small but testable parts of a program one by one
- Start with the part that has the biggest impact (i.e., deals with the hardest problem, takes the biggest step towards “working,” etc.)
- Suggestion: pick one integration algorithm and get its plotting to work
Next
- Loops vs vectorization
- Read section 5.4, except 5.4.2