Texas Instruments TI-89 Developer's Guide

Appendix A: System Routines — Graphing
613
TI
-
89 / TI
-
92 Plus Developer Guide
Not for Distribution
Beta Version January 26, 2001
XCvtFtoP
Declaration:
SSHORT
XCvtFtoP
(BCD16
x
, GR_WIN_VARS *
ptr
)
Category:
Graphing
Description:
Converts the input floating point x coordinate to a pixel column number
based on the specified graph viewing window.
Inputs:
x
— Floating point x coordinate. Valid
x
is not limited to the actual
viewing window, allowing computation of off-screen pixels to the
left (negative) or right of 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 column number or GXY_INVALID if the value computed is
outside the range of SSHORT. The leftmost column in a window is
column 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, YCvtFtoP
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