Specifying R20 per Simulated Curve

[Ian Kleckner]

A user recently brought up the issue that when you simulate data using the Fit RD window, you cannot specify the R20 that you want to use for each curve.

Instead, R20 is simulated as the minimum R2 value observed in the given curve (the value used in simulation is circled in red in the attached figure). This R20 value is not further optimized. Whatever parameters are in that box simply used to draw the curve.

In contrast, when you fit the NoEx model, it is equivalent to assuming dwH = dwX = 0, and then it starts with R20 estimated as min(R2) and then it optimizes the R20 value to minimize Chi2.

I updated GUARDD to specify your own R20 values per curve:

(1) Replace the FitResult.m and GUARDD_fit_rd.m with the two attached files.

(2) Open GUARDD_fit_rd.m and go to line 1559

Set SET_CONSTANT_R20 = true;

Set R20_Fixed_c_array to the array of R20 values you want to simulate

There must be at least one value per curve in the set. If you don't have enough values then the simulation aborts.

(3) Simulate curves as before, and whatever values you type in R20_Fixed_c_array will be used directly.

To disable this feature and use R20 as min(R2) per curve, then go to SET_CONSTANT_R20 = false.