Jerry's Reviews > Basic Computer Programs in Science and Engineering

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it was ok
bookshelves: conviction, retro

Many of the programs in this book would be simple enough to make if you knew the engineering or math they were replicating. For example, the simple factorial program does nothing except multiply successive numbers together until done or the size of the number overwhelms the computer.

More useful is the next program, that shows factorials larger than the computer can handle, though even in this case it isn’t using any special tricks; it is simply checking whether the number is about to be what the programmer thought was too big, and then it divides by 100,000, increments the exponent by 5, and continues, until it is finished.

Several of the programs in the small General Mathematics section are like that: rounding numbers, finding the minimum and maximum of a set of numbers, and so on. Some are more complex, such as finding the Nth root of a number.

Half of the book is taken up by mathematics (simultaneous equations, polynomial evaluator, complex roots and exponents, matrices, data analysis); the rest is electronics (resistor color codes, inductance of a straight wire, Schmitt trigger circuit design, multiple feedback bandpass filter design, for example). the problem with the latter section is that very little is really explained.

The biggest problem I had was with the wire resistance calculator. I was interested in that because I’ve wired up a lamp to use batteries and twelve-volt LEDs instead of AC power, and I was wondering how much power the long wire in the lamp post uses. This program seems to indicate it wouldn’t be much. The program provides calculations for aluminum and for copper wires. Since I thought it seemed useful, I decided to follow his advice that “if other materials are required, the rho for the material will have to be added”. I converted his hard-coded choice of materials to a series of DATA statements and went looking for a list of materials.

But while his results match other calculators I’ve found, his rho numbers do not. There are a lot of lists or rho values for various materials; they are clearly not usable with this program. I ended up searching on the numbers themselves, 17.345 for aluminum and 10.575 for copper, and found two lists that use those numbers rather than the much, much smaller numbers everywhere else. It appears to be that his program uses the “resistivity of metal in ohms per circular mil foot” and at 25 degrees Celsius. But neither his text nor his BASIC remarks mention either of these, which would seem important.

Neither of the two lists provided numbers for anything except copper or aluminum, which may be an indication of some other unstated requirement.

The cross-sectional area is calculated using “105532 * .79304^AWG”, which seems an odd calculation, and is not explained either.

I don’t know enough about the other programs to know if there is a similar problem there.

There’s a note on the half-title page from a previous owner, dated February 18, 1983:

NOTES:
1) Some programs contain typos and/or syntax errors
2) Engineering is NOT thorough
3) User interfaces are primitive and may not trap errors

Which may say a lot about the advances in engineering software between 1980 (when this book was published) and 1983 (when that person used it). Or it might just say a lot about this book’s usefulness.

The idea certainly seems interesting; there are a lot of seemingly useful simple circuits that this lets you adjust values for and see how the new results will come out.
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