opiInitialise_for_SimHenson {OPI}

opiInitialise_for_SimHenson

Description

Simulates responses using a Frequency of Seeing (FoS) curve.

For internal use only, use opiInitialize().

The FoS is modelled as a cumulative Gaussian function over dB with standard deviation equal to min(cap, exp( A * t + B)), where t is the threshold/mean of the FoS in dB. All values are in dB relative to maxStim.

Arguments

type

A single character that is:

• N for using the A and B values from the Normals in Henson et al (2000)

• G for using the A and B values from the Glaucomas in Henson et al (2000)

• C for using the A and B values from the Combined in Henson et al (2000)

• X to specify your own A and B values as parameters

A

Coefficient of t in the formula (ignored if type != 'X').

B

Addend of t in the formula (ignored if type != 'X').

cap

Maximum dB value for the stdev of the FoS curve.

maxStim

The maximum stimulus value (0 dB) in cd/\mbox{m}^2.

...

Any other parameters you like, they are ignored.

Value

A list with elements:

• err NULL if initialised, msg otherwise

Examples

    # Set up a simple simulation for white-on-white perimetry
chooseOpi("SimHenson")
res <- opiInitialize(type = "C", cap = 6)
if (!is.null(res$err))
  stop(paste("opiInitialize() failed:", res$err))