# AIPS HELP file for IMVAL in 31DEC24

#### As of Fri Aug 9 13:41:42 2024

IMVAL: Determines pixel value at specified position w messages

### INPUTS

```INNAME                             Image name(name).
INCLASS                            Image name(class).
INSEQ           0.0      9999.0    Image name(seq. #). 0=>high
INDISK          0.0         9.0    Disk drive #.       0=>any
PIXXY           0.0      4096.0    (X,Y,...) pixel in image
DOCENTER       -1.0         1.0    > 0 -> value at pixel
else cubic interpolate
PIXVAL   @                         Intensity at PIXXY.
COORDINA @                         Coordinates at pixel
ERROR    @                         > 0 => fit failed, else okay
```

### HELP SECTION

```IMVAL
Type: Verb
Use: IMVAL does a cubic interpolation of the image value at the image
location specified by PIXXY (in pixels) and returns the value in
PIXVAL.  The coordinate is also returned.  It reports the pixel
position, pixel value, and coordinates at message level 5.  Verb
QIMVAL is faster since it does not report the results.
INNAME......Image name(name).        Standard defaults.
INCLASS.....Image name(class).       Standard defaults.
INSEQ.......Image name(seq. #).      0 => highest.
INDISK......Disk drive # of image.   0 => any.
PIXXY.......(X,Y,...) pixel location in image.  NOT zero
on the X and Y axes anyway.
DOCENTER....> 0 => find value at closest pixel to PIXXY
<= 0 => do a cubic interpolation about PIXXY
PIXVAL......Intensity at this pixel.
COORDINA....The X and Y coordinates are found as:
Xpos = abs(CO(1)) + abs(CO(2))/60 + abs(CO(3))/3600
if any of CO(1), CO(2), CO(3) < 0: Xpos = -Xpos
Ypos = abs(CO(4)) + abs(CO(5))/60 + abs(CO(6))/3600
if any of CO(4), CO(5), CO(6) < 0: Ypos = -Ypos
Note that, although these are most suited to RA, Dec in
sexagesimal notation, they can be used for any type of
coordinate.  The units are standard FITS units (e.g
degrees, m/sec, Hz, sec, etc.) except that right
ascensions are in hours of time.
ERROR.......If the verb is not aborted for error, but the
interpolation fails, ERROR will be TRUE (1), else
it will be FALSE (-1).
```

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