remove impl details from docs
@@ -130,10 +130,7 @@ delta(cpu_temp_celsius{host="zeus"}[2h])
`deriv(v range-vector)` calculates the per-second derivative of the time series in a range
vector `v`, using [simple linear regression](https://en.wikipedia.org/wiki/Simple_linear_regression).
-The range vector must have at least two samples in order to perform the calculation. The linear
-regression is used to calculate a slope and offset for a trend line, and the slope value is used
-for the derivative calculation. In order to reduce calculation errors, the timestamp of the first
-sample in the range vector is set as `x=0` within the linear regression algorithm. When `+Inf` or
+The range vector must have at least two samples in order to perform the calculation. When `+Inf` or
`-Inf` are found in the range vector, the slope and offset value calculated will be `NaN`.
`deriv` should only be used with gauges.
@@ -335,11 +332,7 @@ January etc.
`t` seconds from now, based on the range vector `v`, using [simple linear
regression](https://en.wikipedia.org/wiki/Simple_linear_regression).
The range vector must have at least two samples in order to perform the
-calculation. The linear regression is used to calculate a slope and offset
-for a trend line, and the slope and offset are used to calculate the predict
-the value of the time series. In order to reduce calculation errors, the
-timestamp of the first sample in the range vector is set as `x=0` within the
-linear regression algorithm. When `+Inf` or `-Inf` are found in the range vector,
+calculation. When `+Inf` or `-Inf` are found in the range vector,
the slope and offset value calculated will be `NaN`.
`predict_linear` should only be used with gauges.
