Arnold Plot is a menu-driven plotting package for Amstrad CPC users at home, school or in business. Everything the user needs to know about is accessed via the main menu. Most of the menu is taken up with the creation and manipulation of the all-important data sets. The user may input a maximum of 15 data sets with a maximum of 50 values per set to give an overall maximum of 750 values in the Arnold Plot database. These data sets can contain any sort of information the user chooses; details of school science projects or business sales charts are equally applicable.

Data is entered into the program via the Data Editor. By accessing the Edit Data Set option new data sets may be created. The edit screen displays a command line along the top, the rest of the screen being divided vertically down the middle. On the left of the dividing line is the chosen name of the data set and the input cursor: up to 15 values may be entered here. The sixteenth and further values are entered on the right-hand side of the dividing line. Corrections such as insertions or deletions can be made easily, so the user will not find it difficult to manipu- late the data. The Data Editor also features more sophisticated options such as the ability to apply an expression such as X + 10 to given values; it will work out calculations such as the average and can perform more complex polynomial equations as well.

Data sets can be saved and reloaded when the user needs them and all sets in memory are noted in the index in the main menu. Once the user has satisfactorily entered his data, he can access the plot menu from the main menu. The plot screen is divided into three parts. At the top is the command line and space for user instructions. There is a large area to display graphs and at the bottom of the screen there is a separate section in which to display information and error messages. Data sets can be plotted as graphs, bar charts, histograms, high-low charts and pie charts. Further options are for fines, symbols, or lines and symbols graphs, and there are three types of bar charts and histograms: centre, left and right.

When first accessing the plot menu, the user must choose which type of display he needs; then he must make these further choices before he can start specifying which data set goes on which axis. After that, everything is plain sailing.

The plot menu allows overlaying of graphs or bar charts on graphs, but the other plot types may only be overlaid by similar plots. There may be no more than fifteen overlays, only three in the case of pie charts. This is as much because of the need to avoid overcrowding as it is because the program capacity is being filled up. Plots can also be re-scaled and labelled up to fifteen times with whatever notes the user chooses.

When all necessary adjustments have been made, the final product may be printed out. Users do not need to have an expensive plotter to get good results from this program. A hard copy of the plot can be obtained by a screen dump to dot matrix printer or by the use of a pen-plotter such as the MCP 40.

Throughout the program, instructions are delivered on-screen and the manual is very easy to read, if a little cramped. Error messages or user mistakes are accompanied by low-tone beeps from the machine. These beeps should be treated as warnings unless otherwise specified in the manual.

Users will also notice that the program is capable of being set for colour or green-tube monitor (default colour). Here is another example of how the program caters for a wide range of users; with a standard hardware set, good-looking results can be produced for whatever purpose. Users needing more professional-looking hard copy have only to use the right machinery.

This program can cope with both worlds. As long as the user knows what he wants to do, there should be no problems. The manual is readable and instructive with plenty of examples for the user to follow. There is example data supplied on the disc.

Arnold Plot is a flexible, affordable program which can give CPC users capabilities so far monopolised by owners of more complex machines.