The Rescale Operation
(v 4.1)

One of the simplest, yet most powerful, features of XYPLOT is the Rescale operation. It allows you to modify at once all the x or y values of a data set. With Rescale you may apply a function to x or y, or perform arithmetic operations between x or y and a constant. The various types of rescale operations supported by XYPLOT are shown below.

trigonometric sin(x) cos(x) tan(x) atn(x)
angular rad –> deg deg –> rad
base e ex log(x)
base 10 10x log10(x)
powers xp px
arithmetic x + c x - c c - x cx x/c c/x
polynomial a+bx+cx2+dx3+…

Using Rescale

From the plot display screen, click on the Math menu and select Rescale. At the input prompt,

Rescale >>

you may enter simple expressions such as cos(y), x/10, exp(y), d>r(x), y+2, etc.. You may use either upper or lower case and the parentheses around function arguments are optional. Some things to note are: Rescale always acts on all x or y entries in the data set, and replaces each entry with the result of the operation. For example, the expression
produces the substitution
y –> cos(y)
for every y in the data set. The data stored in memory are actually modified by Rescale. That is why the plot will change with each operation. A note is added to the beginning of the data set's header automatically to record the history of the modifications.

Examples of Rescale Expressions

Here are examples to illustrate some of the rescale operations that are possible.

(to create this…
type this)
x + 5 x+5
y/2.5 y/2.5
3.0 - y 3.0-y
y2 y^2
1 + 5x + 2.4x2 pol(x, 1, 5, 2.4)
10x 10^x
1/y 1/y
y*3.14 y*3.14
log10(x) l10(x)
ln(y) log(y)
ex exp(x)
sin(y) sin(y)
iy y*(0, 1)

only for complex datasets

See also examples of usage.