How to caculate the log2foldchange?

Question

[Sindy]

Hello, I want to know the formula about the log2foldchange. For example, there is the data: control: 31.975 (TPM value) drought 1 hour: 10.990 drought 6 hour: 6.600 how to caculate the log2foldchange? What's the formula?

Answer 1

[EagleEye]

Drought1:

Log2(10.990/31.975)

Drought2:

log2(6.600/31.975)

Drought1 vs Drought2:

abs(log2(6.600/10.990))

ABS = Absolute value (you can find this function in R, Matlab and also in Excel)

Note: In Excel the equation goes like this, ABS(Log(6.600/10.990,2))