Exponential calculation

Hi, I am new to qt
I would like to perform a exponential calculation according to this formula:
C= C0 * exp (-k * time)

I would like to construct an interface with 2 fields (C0 and k(constant) where the user fill in these two parameters.

The results (C) should be presented in a textfield with a new results every second.
like this (example):
C1 (1 second) = 0.111
C2 (2 seconds) = 0.121
and so on...

I would appreciate any help!
Thomas

Any C++ reference book for the math part.
From the Qt documentation (Assistant): QDoubleSpinBox, QLabel, QPushButton, QPlainTextEdit, QString, QTimer, Signals and slots, the tutorials and lots of the examples