Why scale B1 in this method?

[ShannonZ]

The following code snippet was adopted from function DoB1Scaling: `function rfGain=DoB1Scaling(PulSeg,dt,ActFA)

global VObj;

flag=zeros(size(PulSeg)); ind=diff(abs(PulSeg)); flag(find(ind<0)+1)=1; flag(ind>=0)=1; rfGain=((ActFA/180)pi)/(VObj.Gyrosum(PulSeg.*flag)*dt);`

What's the reason for these operations?

[leoliuf]

The main purpose of this scaling is to ensure the prescribed flip angle is achieved for some excitation pulses.