Summary:
The amplified SegReg computer program (model,
calculator), SegRegA, originally designed to
perform a segmented (piecewise) linear
regression, has been given the possibility to fit
power curves, quadratic parabola's,
cubic functions, and sigmoid Scurves to
agricultural crop data,(see
list of publications
in which SegReg is used).
An example of the application of the logistic
Scurve can be found in the article: "Applying
SegRegA to the annual average temperature trend
from 1900 to 2020 in the Netherlands resulting
from global warming; analysis by segmented linear
regression types and curved functions such as
the Scurve, Power curve, generalized quadratic
and cubic regressions". Download from:
average
temperature.pdf
The cubic functions are determined by matrices,
determinants and matrix inversion.
The third degree polygon can be used as a method
to calculate and determine the salt tolerance of
crops, see
this article
published in the International Journal of
Agricultural Science and entitled "Crop tolerance
to soil salinity, statistical analysis of
data measured in farm lands".
An overview of the use of Scurves is given in
this text file

Critical reviews:
A critical review of the use of Scurves for the
determination of a salt tolerance index for crops
is to be found in
this report
Another critical review of the use of Scurves
with the same purpose in various published
papers can be seen in
this commentary

Screenprint:


Download:
SegReg
standard
Download:
SegRegA
amplified
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