i have two set of data for temperature measurements which vary depends on each other. the variation may be divided into three portions. how can we seperate these portions

i have two set of data for temperature measurements which vary depends on each other. the variation may be divided into three portions maybe fisrt portion is linear and followed by a curved portion in the graph (may be exponential) and again linear increase. I also have the data for these two temperatures

[JINU SUDHAKARAN Mr]

The blue one is the important one. we need to select the region based on the blue one. initally a linear portion and then a curved portion. we need to divide the data exactly at the point in between these portion. how we can find that point?

Answer 1

[Alan Stevens]

Here's a possible way (assumes the data is already in the workspace):

dT2 = gradient(T2);
minval = min(dT2(Time<2.5));
ix = find(dT2(Time<2.5)==minval);
T2lin = T2(1:ix); T2nonlin = T2(ix+1:end);
plot(Time(1:ix),T2lin,Time(ix+1:end),T2nonlin),grid