Beginning-of-period uniform payment series

Posted on May 14, 2019 by Patricio Paez

Textbooks on economic analysis define a formula to calculate the equivalent future value F of a series of uniform payments A for n periods at interest rate i.  It is assumed that the payments occur at the end of each period.   Rent, insurance payments or deposits into a savings account occur are beginning-of-period cash flows.  What formula should we use in these cases to calculate the equivalent future value? Continue reading →

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Cómo encontrar la fuente de una noticia digital

Posted on May 10, 2019 by Patricio Paez

Día a día vemos noticias: En nuestro correo electrónico, en sitios web (blogs, noticiarios) y en plataformas (WhatsApp, Twitter, Facebook). Es muy común que nos envíen solamente una copia del texto o del video de la noticia, sin la referencia a la fuente.

¿Cómo saber quién publicó la noticia, cuándo y dónde? Continue reading →

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Visualizando la cuantía de la pensión imss de 1973

Posted on November 5, 2018 by Patricio Paez

El artículo 167 de la Ley del Seguro Social anterior, publicada en 1973 y abrogada en 1995, indica cómo se calcula el monto de la pensión de vejez o invalidez, en base a un par de porcentajes incluídos en una tabla.  ¿Qué pasa si mostramos gráficamente la  información de la tabla? Continue reading →

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Install GnuCash in Debian testing from stable

Posted on September 7, 2018 by Patricio Paez

GnuCash in Debian unstable fails, how can I get a working GnuCash in Debian testing?

Continue reading →

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Install GnuCash in Debian testing from unstable

Posted on January 1, 2018 by Patricio Paez

I just found that gnucash is not available in Debian testing! How do I install it then? Continue reading →

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Concatenating strings with punctuation

Posted on July 22, 2017 by Patricio Paez

Creating strings of the form “a, b, c and d” from a list [‘a’, ‘b’, ‘c’, ‘d’] is a task I faced some time ago, as I needed to include such strings in some HTML documents. The “,” and the “and” are included according to the amount of elements. [‘a’, ‘b’] yields “a and b“, [‘a’] yields “a” for example. In a recent review to the code, I changed the method from using string concatenation:

if len(items) > 1:
    text = items[0]
    for item in items[1:-1]:
        text += ', ' + item
    text += ' and ' + items[-1]
else:
    text = items[0]

to the use of slicing of the items list, addition of the resulting sublists and str.join to include the punctuation:

first = items[:1]
middle = items[1:-1]
last = items[1:][-1:]
first_middle = [', '.join(first + middle)]
text = ' and '.join(first_middle + last)

The old method requires an additonal elif branch to work when items is an empty list; the new method returns an empty string if the items list is empty. I share this tip in case it is useful to someone else.

Posted in Python, Tips and tricks | 2 Comments

Analysis of the silent key failure in the Clavinova CLP810s piano

Posted on June 19, 2015 by Patricio Paez

In order to understand the silent key failure, I went through different steps to get more information. Continue reading →

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Keyboard scanning in the Clavinova CLP810s piano

Posted on May 29, 2015 by Patricio Paez

How is keyboard scanning implemented in the CLP810s piano? Continue reading →

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Silent keys, noisy keyboard on our Clavinova CLP810s piano

Posted on May 20, 2015 by Patricio Paez

We purchased a new Clavinova CLP810s digital piano for our home back in December 1999. The piano sound is great and the instrument performed fine initially, unfortunately, a few months after the piano arrived, Continue reading →

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GParted unable to satisfy all constraints on the partition

Posted on June 17, 2013 by Patricio Paez

Using GParted to move up the start of an extended partition and of the enclosed logical partition, resulted in the error: Unable to satisfy all constraints on the partition.

The solution was to disable the alignment requirement for the extended partition.  Using an alignment for the logical partition enclosed in the extended partition was fine.

I post this here to remind me of the solution and in case someone else has the same problem.  These are the best answers that I found leading to the solution:

Unable to satisfy all constraints on the partition (ubuntuforums.org)

Problem: “Unable to satisfy all constraints on the partition.” (GParted forum)

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