Texas Instruments TI-89 - Xcvtptof

614
Appendix A: System Routines — Graphing
TI
-
89 / TI
-
92 Plus Developer Guide
Not for Distribution
Beta Version January 26, 2001
XCvtPtoF
Declaration:
BCD16
XCvtPtoF
(SSHORT
x
, GR_WIN_VARS *
ptr
)
Category:
Graphing
Description:
Converts pixel column number
x
to the corresponding floating point x
coordinate at the center of that column, based on the specified graph
viewing window.
Inputs:
x
— Column number. The leftmost column is column 0 in all graph
windows. Valid column numbers are not limited to the actual
window width, allowing computation for off-screen values to the
left (negative column number) 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 the x coordinate at the center of column
x
in BCD16 floating point
format, rounded to 12 digits.
Assumptions:
Assumes an x, y coordinate system, even in 3D mode.
Side Effects:
Possible overflow error.
Availability:
All versions of the TI-89 / TI-92 Plus.
TI
-
89 / TI
-
92 Plus
Differences:
None
See Also: XCvtFtoP, CptFuncX, YCvtPtoF, YCvtFtoP
Example:
for( col=0; col <= maxpix; ++col )
{
/* compute BCD x value corresponding to next pixel to plot */
xplot = XCvtPtoF( col, gr_active );
.
.
.
}