DollarLink News -- September 30, 1996

Enhancements Added

Up to 20 Terms In Custom Index

We have been able to increase the maximum number of terms in a custom index from 10 to 20. This should reduce the number of custom indices that are needed to compute a formula that may have more than 10 terms. The previous approach to compute an index with, say, 60 components was to create six custom indices, each with 10 terms, and then a seventh index that sums the first six indices. Now you have to define only three custom indices and then a fourth one to sum the three indices.

Example

Suppose you wanted to add the current prices of 50 stocks. Since the maximum number of terms a custom index can evaluate is 20, you have to add up several custom indices together.

There are two ways of doing this.

The first is to break up the set of 50 stocks into sets of 20, 20 and 10 stocks and then add the custom indices that evaluate each set. The definition formulas would be

 
$$1 =  1.0 * S1 + 1.0 * S2 + ... + 1.0 * S20  
$$2 =  1.0 * S21 + 1.0 * S22 + ... + 1.0 * S40  
$$3 =  1.0 * S41 + 1.0 * S42 + ... + 1.0 * S50  
$$4 =  1.0 * $$1 + 1.0 * $$2 + 1.0 * $$3

where S1, S2, ..., S50 are the various stocks you want to add up.

The other way is to chain these stocks as follows:

  
$$C1 =  1.0 * S1 + 1.0 * S2 + ... + 1.0 * S20  
$$C2 =  1.0 * S21 + 1.0 * S22 + ... + 1.0 * S39 + 1.0 * $$C1 
$$C3 =  1.0 * S40 + 1.0 * S41 + ... + 1.0 * S50 + 1.0 * $$C2

In this example, the custom index $$C3 is equivalent to the above custom index $$4.

We call it chaining because custom index $$C1 is part of the custom index $$C2 and $$C2 is part of the index $$C3. They act as a link between indices.

There is no particular advantage of either approach and you should use whichever approach you find more confortable.

Remember that you have to worry about overflowing the numbers. In the examples here we used 1.0 as the coefficient for each term in the sums. It is possible that adding the prices of 20 stocks would result in a number greater than 1600. Therefore, it is probably better to use 0.001 in this example as the coefficient for each term and then to remember that the resulting sum is in thousands of dollars.

Using DollarLink under Windows 95

It has been a year since Windows 95 was introduced and we have been using it for several months to run DollarLink.

Although we feel that it is always better to use DOS to run DollarLink, some of our customers find it convenient to multitask. Windows 95 will do that better than Windows 3.1. Win 95 appears to be more stable than Win 3.1, but it still is not rock-solid.

DollarLink seems to run a bit faster in a DOS session under Win95 than under Win 3.1. This is probably because of the 32-bit hard disk access that Win 95 provides its DOS sessions. However, DollarLink still runs faster in regular DOS outside of Win 95. It is easier to run DollarLink in a DOS session under Windows 95 than Windows 3.1. All you have to do is find the MS-DOS icon on the desktop (or with the file manager program called Explorer that comes with Win 95) and click on it. That will open up a DOS screen with a C prompt. That screen may occupy either a portion of the PC screen or the full screen. (You can toggle that setting with Alt+ENTER key combination.) We prefer letting DollarLink take up the entire PC screen.

Unlike Win 3.1, you don't have to create a .pif file. To put DollarLink into the background so that it continues to run, use the Alt+Tab key combination to rotate between different applications that are active.

Beware that before you put DollarLink into the background you should have DollarLink in the text mode . If you put it into the background while you are in graphics mode, Win 95 will suspend it and not process quotes until you put it into the foreground again.

If you are going to run DollarLink in a DOS session under Win 95, start DollarLink with

 
$$  [enter]

The double $$ command is just like the single $ command except that it does not try to reboot the PC at midnight. (It just goes back into DollarLink after midnight.) This is particularly useful if you want to run DollarLink continuously for more than 24 hours.

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