Lecture12_Array_Operation

Tutorials:

1. Array has the following frequently used operators:


Array addition and subtraction are being conducted in 'element-wise' automatically.


Notes:
HOWEVER
Multiplication and Division are using different rules!!!!
For element-wise operation, you have to have a '.' before the operator!!
For example:


Also, built-in functions also work element-by-element, which means the function will apply to every element in the array at the same time.


However, when multiplying or dividing these functions, or when raising them to a power, you must use element-by-element operations if the arguments are arrays. For example, if x is a vector, then to compute z = sqrt(x) sin(x), you must type: z = sqrt(x).*sin(x)

Please tell me what are the highlighted operations represent?


2. Array Functions
There are many array functions sum, mean, median, min, max, sort, std, etc.





3. Non-elementwise array (matrix) mutiplications:
What if you don't use '.' in multiplication and division

Two arrays (matrix) multiplication:


Another IMPORTANT thing: Matrix notatino can represent equations:




Now, let's take care of a 'serious' matrix:











IMPORTANT






End of the tutorial...

Now, starts the in-class tasks you need to submit, due Wed.









(Y = log(X) returns the natural logarithm ln(x) of each element in array X.)

No other homework other than these four in-class problems. Publish your results in one 'html' file and send it to homeworkflc02@gmail.com by Wed.