What is temperature gradient? When is the temperature gradient considered positive and when is it considered negative?

(N/A) The temperature gradient is defined as the rate of change of temperature with respect to distance in the direction of heat flow. Mathematically,it is expressed as $\frac{dT}{dx}$.
$1$. If the temperature difference is measured from the hot end towards the cold end (i.e.,in the direction of heat flow),the temperature decreases as distance increases. Thus,$\frac{dT}{dx}$ is negative.
$2$. If the temperature difference is measured from the cold end towards the hot end (i.e.,opposite to the direction of heat flow),the temperature increases as distance increases. Thus,$\frac{dT}{dx}$ is positive.