I have two floats in Python that I'd like to subtract, i.e.

v1 = float(value1)
v2 = float(value2)
diff = v1 - v2

I want "diff" to be computed up to two decimal places, that is compute it using %.2f of v1 and %.2f of v2. How can I do this? I know how to print v1 and v2 up to two decimals, but not how to do arithmetic like that.

The particular issue I am trying to avoid is this. Suppose that:

v1 = 0.982769777778
v2 = 0.985980444444
diff = v1 - v2

and then I print to file the following:

myfile.write("%.2f\t%.2f\t%.2f\n" %(v1, v2, diff))

then I will get the output: 0.98 0.99 0.00, suggesting that there's no difference between v1 and v2, even though the printed result suggests there's a 0.01 difference. How can I get around this?

thanks.