NMRPipe Processing Functions
ADD: Add a Constant to Data.

ADD adds a constant to the real or imaginary part of each vector in the data stream, or to a range of points within each vector. It is possible to specify separate constants to add to the real and imaginary parts of the data, however the imaginary constant will only be used if the current dimension of the input data has an imaginary part.

OPTIONS

-c cC
Specifies the same constant to add to both the real part of the data, and also to the imaginary part if it exists.

-r cR
Specifies the constant to add to the real part of the data.

-i cI
Specifies the constant to add to the imaginary part of the data. This has no effect if the input data has no imaginary part.

-ri
If this flag is used, the imaginary part of the data will be added to the real part, and flags -r realC -i imagC and -c riC will be ignored. The -ri flag is ignored if the input data has no imaginary part.

-x1 pnt1
Specifies the location of the first point in range of points to adjust, with default units in points. The default value is 1, the first point in the data vector. The valid unit labels are: Pts Hz ppm %. When specifying a location with a unit label, there should be no spaces between the numerical value and the label.

-xn pntN
Specifies the location of the last point in range of points to adjust, with default units in points. The default value is the last point in the data vector. The valid unit labels are: Pts Hz ppm %. When specifying a location with a unit label, there should be no spaces between the numerical value and the label.

EXAMPLES

The following example adds the constant 1.0 to all points:

   nmrPipe -fn ADD -c 1.0

The following example adds the constant 1.0 to all real points, and -1.0 to all imaginary points, if any:

   nmrPipe -fn ADD -r 1.0 -i -1.0

The following example adds the constant "100.0" to the range of points from 5.5ppm to 4.5ppm:

   nmrPipe -fn ADD -c 100.0 -x1 5.5ppm -xn 4.5ppm

The following C-shell script uses the program scale2D to extract the minimum and maximum values in a given spectrum. A processing scheme with the ADD function is used to add a suitable constant to the spectrum so that there will be no negative values in the result. The script uses the commands MATH and IMATH to evaluate floating-point arithmetic.

#!/bin/csh

set sInfo  = (`scale2D test.ft2`)
set minVal = $sInfo[3]

echo Minimum is $minVal

if (`IMATH "$minVal < 0.0"`) then
   set c = (`MATH "1.0 + -1.0*$minVal"`)
   echo Minimum is less than zero, adding $c
   nmrPipe -in test.ft2 -fn ADD -c $c -out test.ft2 -inPlace
endif

SEE ALSO

The ADD function has corresponding functions SET and MULT.

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