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  • Don Abril 8:14 am on May 21, 2017 Permalink | Reply

    Matrices Everywhere 

    Yet another semester has ended to culminate in another myriad of memories to cherish.

    The lesson that made an impact on me was the one about Gauss-Jordan Elimination kasi impakto talaga yung topic na yun. But in all seriousness, I’d say the lesson held enough of my attention to make more or less of an impact on me, as I found it quite curious and annoyingly interesting that you can turn certain matrices of not-so-friendly values into ones that look so simple and friendly that they’d be puppies had they been animals.

    I’d summarize the course with one word: MATRICES. I’m willing to bet that not one of the students who took the course would deny the sheer amount of matrices that we saw over the semester. Funnily, I have been encountering matrix multiplication since my first year in college, each time having to ask how it worked because somehow the process didn’t ever get through my thick skull. However, thanks to CS 130, I don’t see myself forgetting this again.

    Final words, well well.

    I give my thanks to Sir Paul. It is commendable that you are not only an effective instructor, but also a friend among us students.

    I thank my project groupmates (most of whom also happen to be my quiz groupmates, and for which I also give thanks) for the final project, and for being some of the new friends I’ve made this semester. Special thanks to Paul Sason na nagsalba sa final project woohoo!

    Lastly, my classmates also receive my gratitude. I don’t know every one of you, but I don’t mind. We had fun.

    Cheers, and see you around! 🙂

  • Don Abril 1:59 pm on May 6, 2017 Permalink | Reply

    Fourier Transform in Synthetic Aperture Radar Systems 

    Synthetic Aperture Radar

    A synthetic aperture radar (or simply SAR) is an imaging radar system that uses the recorded echoes of electromagnetic waves transmitted by an antenna to produce images. As an example, shown below is an image of Mount Teide in Spain, synthesized by a SAR system installed on the now-retired space shuttle Endeavour [1].


    What role does Fourier Transform play in SAR systems?

    First, we have to establish that for many applications, the measurements of a SAR system (relevant to the echoes recorded by the antenna) are taken along a more-or-less linear path, as in a case where the SAR is mounted or installed on an airplane. This way, A SAR antenna is at different points at different times during the measurement process.

    It is easy to imagine that generating an image by simply collating individual antenna measurements would result in one in which the same images are overlapping. This is where Fourier transform comes into play. ” In order to efficiently convert these measurements into a SAR image, the data are first [re-sampled] onto an equally spaced rectangular grid and then transformed into the image domain by a fast Fourier transform.” [2] This Fourier method allows the SAR system to synthesize, using the recorded information, an image that approximates what the object looks like in reality.


    1. https://en.wikipedia.org/wiki/Synthetic_aperture_radar
    2. bshttp://www.maths.lth.se/~fa/preprints/SAR_andersson_moses_natterer.pdf, (Fast Fourier Methods for Synthetic Aperture Radar Imaging, Andersson et al.)
  • Don Abril 4:06 am on February 12, 2017 Permalink | Reply

    Symmetry in the Rorschach Test 


    The Rorschach (pronounced “roar-shack”) test is a well-known though controversial psychoanalytic test developed by its namesake Hermann Rorschach back in the early 1900s. The test consists of symmetrical images of inkblots on paper, which are shown to patients to evoke some kind of reaction for the psychologist to interpret.

    You might be wondering, if he wanted to draw reactions from his patients, why opt for symmetry? Hermann Rorschach himself explained when he published his work:

    “Asymmetric figures are rejected by many subjects; symmetry supplied part of the necessary artistic composition. It has a disadvantage in that it tends to make answers somewhat stereotyped. On the other hand, symmetry makes conditions the same for right and left handed subjects; furthermore, it facilitates interpretation for certain blocked subjects. Finally, symmetry makes possible the interpretation of whole scenes.”

    We may conclude that Rorschach made his inkblot images symmetric to accommodate different predispositions and ways of thinking in people.

    Trivia (makaka-relate yung mahilig sa superhero movies) : The Rorschach test’s inkblot images were used as a basis for the mask of one of  Watchmen’s (2009) characters, a ruthless vigilante conveniently named Rorschach.



  • Don Abril 1:25 am on January 30, 2017 Permalink | Reply

    Vectors in Magnetic Flux 

    Flux, defined generally, is the amount of “something” that passes through a surface. In electromagnetism, magnetic flux is the number of magnetic field lines passing through an area. While flux in this context is a scalar quantity, measuring it requires the presence of a magnetic field (which in itself is a vector field, i.e. a collection of arrows with a given magnitude and direction). Getting the magnetic flux through a surface is done by calculating the surface integral of the normal component of the magnetic field passing through that same surface.


  • Don Abril 5:27 am on January 21, 2017 Permalink | Reply

    Hello all. 

    • What’s your name?

    My name is Don Rodolfo Padilla Abril. My nicknames include Don, Doño, DR, and Utoy as a reference to a Pugad Baboy character. Just call me Don. A little trivia: I am the second Don in the family, the first being my only brother Don Julio. Our names were taken from our father Rodolfo Julio. Share lang.

    • What were your thoughts when you enrolled in this course?

    Upon taking this course I knew I would be facing a lot of hard work as I have before with other math-intensive subjects.

    • How comfortable are you with math?

    I’ve always said that I have a love-hate relationship with math. Whether I’m comfortable with it or not depends on the specific subject matter I’m currently tackling. For instance, I hated Math 17, but loved Math 53. There are topics that come smoothly and there are topics that don’t. Simply put, I’m about as comfortable with math as it allows me to be.

    • What’s your dominant feeling right now?

    I’ve just finished with a satisfying meal after a tiring 2-hour trip, and all that I can think of is the sweet, sweet caress of a mattress and pillows. I feel sleepy.

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