Tip 89. Coefficients for units   Fig. 89. Coefficients for units of measure

The system of measure of physical values that is built-in in Mathcad is rather illogical. For example, in this program there are km, cm and mm (kilometer, centimeter and millimeter), but there are not units divisible by Pascal – unite of measure of pressure (kPa, MPa and etc.), though Pascal (Pa, Newton by square meter) is used very seldom without factors. Because of it user of Mathcad has to introduce auxiliary (user’s) units of measure of pressure (kPa := 103 Pa, МPа := 106  and etc.) and other physical values (ms := 10-3 sec and etc.). This problem can be solved if we introduce coefficients divisible by ten (see fig. 89) but not new units of measure. After it if we change unit of measure that is printed in addition to dimensional value (see tip 4) or during input of unit of measure we can put in multiplication of the factor on built-in unit, pouring them together (k×Pa ® kPa and etc.) by change of the multiplication sign (see the dialogue windows in the fig. 89) to absentee blank (No Space).

With help of this advise, running counter to tip 9, where was said that never it is worth to leave out the sign of multiplication we find new question: what does it mean mm? – it is millimeter or square mater (m×m, where product point (×) is changed to absentee blank). Indeed such ambiguous interpretations meet not only in Mathcad: mkg – what does it mean? – it is microgram (mk×g) or millikilogram (m×kg) i.е. gram. Here it is better to write mg and everything will be clear. Kilogram is enough strange unit: it is one in “magnificent seven” SI (International System of Units) that is formed by form but united (main) by matter.

Remark. The problem of mm (see above) can be solved if we choose different styles for the first and second letter m (see tip 52): the first m is user’s constant 10-3 but the second one is built-in unit of measure of length (meter).

 кПа:=103×Pa, if we have in mind Russian user of Mathcad.

 These m can be painted in different colors, but it will be too variegated.