The R►Pr( Command

Command Summary

R►Pr( calculates the radius component (in polar coordinates) given the Cartesian coordinates.

Command Syntax

R►Pr(x,y)

Press:

1. 2nd ANGLE to access the angle menu.
2. 5 to select R►Pr(, or use arrows and ENTER.

TI-83/84/+/SE

1 byte

R►Pr( (Rectangular to polar radius) takes the (x,y) (Cartesian) coordinates, and gives the radius coordinate r of the same point in (r,θ) (polar) mode. The identity used for this conversion is r² = x²+y²

R►Pr(3,4)
5
√(3²+4²)
5
R►Pr({6,5},{8,12})
{10 13}


The function works even when the equivalent √(x²+y²) fails due to overflow:

R►Pr(3e99,4e99)
5e99


# Optimization

R►Pr( is the smallest way to implement the distance formula $d=\sqrt{(x_1-x_2)^2+(y_1-y_2)^2}$. Just pass it the values x1-x2 and y1 - y2 as arguments:

:√((5-2)²+(4-0)²)
can be
:R►Pr(5-2,4-0)


.