Texas Instruments TI-89 Developer's Guide

Appendix A: System Routines — Graphing
615
TI
-
89 / TI
-
92 Plus Developer Guide
Not for Distribution
Beta Version January 26, 2001
YCvtFtoP
Declaration:
SSHORT
YCvtFtoP
(BCD16
y
, GR_WIN_VARS *
ptr
)
Category:
Graphing
Description:
Converts the input floating point y coordinate to a pixel row number based
on the specified graph viewing window.
Inputs:
y
— Floating point y coordinate. Valid
y
is not limited to the actual
viewing window, allowing computation of off-screen pixels above
(negative) or below the visible window.
ptr
— Pointer to the GR_WIN_VARS struct to use for viewing window
values (
gr_active
for the active graph window,
gr_other
for the
second graph in two graph mode).
Outputs:
Returns a pixel row number or GXY_INVALID if the value computed is
outside the range of SSHORT. The topmost row in a window is row 0.
Assumptions:
Assumes an x, y coordinate system, even in 3D mode.
Side Effects:
None
Availability:
All versions of the TI-89 / TI-92 Plus.
TI
-
89 / TI
-
92 Plus
Differences:
None
See Also: XCvtPtoF, CptFuncX, YCvtPtoF, XCvtFtoP
Example:
/* convert float coordinates to pixel coordinates and plot point on the pixel */
col = XCvtFtoP( x, gr_active ); /* find pixel column */
row = YCvtFtoP( y, gr_active ); /* find pixel row */
WinPixSet( gr_active->grwinp, col, row ); /* plot point */

Texas Instruments TI-89 Specifications

General

Display size (HxV)	100 x 160 mm
Memory type	639K FLASH ROM, 188K bytes RAM
Compatible operating systems	Operating System 2.09
Battery type	AAA