Smalltalk › Squeak › Squeak - Dev

The Trunk: Graphics-nice.86.mcz

_‹ Previous Topic Next Topic _›

Classic

List

Threaded

2 messages Options

commits-2

The Trunk: Graphics-nice.86.mcz

Nicolas Cellier uploaded a new version of Graphics to project The Trunk:
http://source.squeak.org/trunk/Graphics-nice.86.mcz

==================== Summary ====================

Name: Graphics-nice.86
Author: nice
Time: 31 October 2009, 3:13:31 am
UUID: 67835c13-ecca-4ff8-8635-e8f15d789607
Ancestors: Graphics-nice.85

while at arcTan: fix 2 ULP in Float theta
Note that Float theta is in [0,2*pi[ while arcTan: is in [-pi,pi]
(0@0) theta leads to pi/2 instead of 0 for new version of arcTan: (pi for old version)
#arcTan: does handle case of negativeZero, #theta doesn't

=============== Diff against Graphics-nice.85 ===============

Item was changed:
----- Method: Point>>theta (in category 'polar coordinates') -----
theta
"Answer the angle the receiver makes with origin in radians. right is 0;
down is 90.
Corrected the constants from single precision to 64 Bit precision
and changed the sends in case of overflow to constants HK 2005-07-23"

| tan theta |
x = 0
ifTrue: [y >= 0
+ ifTrue: [^ 1.5707963267948966 "90.0 degreesToRadians"]
- ifTrue: [^ 1.570796326794897 "90.0 degreesToRadians"]
ifFalse: [^ 4.71238898038469 "270.0 degreesToRadians"]]
ifFalse:
[tan := y asFloat / x asFloat.
theta := tan arcTan.
x >= 0
ifTrue: [y >= 0
ifTrue: [^theta]
ifFalse: [^"360.0 degreesToRadians" 6.283185307179586 + theta]]
ifFalse: [^"180.0 degreesToRadians" 3.141592653589793 + theta]]!

Nicolas Cellier

Re: The Trunk: Graphics-nice.86.mcz

Note that more variants of this code are found in
Complex>>#arg
Point>>#degrees this one was probably unnecessary,
^self theta radiansToDegrees would be as accurate knowing that
{Float halfPi radiansToDegrees - 90.
Float pi radiansToDegrees - 180.
(Float pi + Float halfPi) radiansToDegrees - 270.
Float twoPi radiansToDegrees - 360} allSatisfy: [:e | e = 0]
Point>>#bearingToPoint: (same as degrees but shifted 90°
counterclockwise just to have 0° at north - that is upscreen).

2009/10/31 <[hidden email]>:

> Nicolas Cellier uploaded a new version of Graphics to project The Trunk:
> http://source.squeak.org/trunk/Graphics-nice.86.mcz
>
> ==================== Summary ====================
>
> Name: Graphics-nice.86
> Author: nice
> Time: 31 October 2009, 3:13:31 am
> UUID: 67835c13-ecca-4ff8-8635-e8f15d789607
> Ancestors: Graphics-nice.85
>
> while at arcTan: fix 2 ULP in Float theta
> Note that Float theta is in [0,2*pi[ while arcTan: is in [-pi,pi]
> (0@0) theta leads to pi/2 instead of 0 for new version of arcTan: (pi for old version)
> #arcTan: does handle case of negativeZero, #theta doesn't
>
>
> =============== Diff against Graphics-nice.85 ===============
>
> Item was changed:
> ----- Method: Point>>theta (in category 'polar coordinates') -----
> theta
> "Answer the angle the receiver makes with origin in radians. right is 0;
> down is 90.
> Corrected the constants from single precision to 64 Bit precision
> and changed the sends in case of overflow to constants HK 2005-07-23"
>
> | tan theta |
> x = 0
> ifTrue: [y >= 0
> + ifTrue: [^ 1.5707963267948966 "90.0 degreesToRadians"]
> - ifTrue: [^ 1.570796326794897 "90.0 degreesToRadians"]
> ifFalse: [^ 4.71238898038469 "270.0 degreesToRadians"]]
> ifFalse:
> [tan := y asFloat / x asFloat.
> theta := tan arcTan.
> x >= 0
> ifTrue: [y >= 0
> ifTrue: [^theta]
> ifFalse: [^"360.0 degreesToRadians" 6.283185307179586 + theta]]
> ifFalse: [^"180.0 degreesToRadians" 3.141592653589793 + theta]]!
>
>
>