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Exercise 1

How would you simplify the following loop conditional? 



      DO I=1,N
        A(I) = A(I) * B
        IF (I .EQ. N/2) A(I) = 0. 
      ENDDO

Exercise 2

Time this loop on your computer, both with and without the test. Run it with three sets of data: one with all A(I)s less than SMALL, one with all A(I)s greater than SMALL, and one with an even split. When is it better to leave the test in the loop, if ever? 



      PARAMETER (SMALL = 1.E-20) 
      DO I=1,N
        IF (ABS(A(I)) .GE. SMALL) THEN 
          B(I) = B(I) + A(I) * C
        ENDIF 
      ENDDO

Exercise 3

Write a simple program that calls a simple subroutine in its inner loop. Time the program execution. Then tell the compiler to inline the routine and test the performance again. Finally, modify the code to perform the operations in the body of the loop and time the code. Which option ran faster? You may have to look at the generated machine code to figure out why.

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Definition of a lens

Lenses

A lens is a custom view of the content in the repository. You can think of it as a fancy kind of list that will let you see content through the eyes of organizations and people you trust.

What is in a lens?

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Who can create a lens?

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| A lens I own (?)

Definition of a lens

Lenses

A lens is a custom view of the content in the repository. You can think of it as a fancy kind of list that will let you see content through the eyes of organizations and people you trust.

What is in a lens?

Lens makers point to materials (modules and collections), creating a guide that includes their own comments and descriptive tags about the content.

Who can create a lens?

Any individual member, a community, or a respected organization.

What are tags? tag icon

Tags are descriptors added by lens makers to help label content, attaching a vocabulary that is meaningful in the context of the lens.

| External bookmarks