---
title: "Nested Formulas and Advanced Functions"
slug: 2023-09-22-nested-formulas-and-advanced-functions
date: 2023-09-22
type: new
tags: ["library"]
url: https://invertbio.com/changelog/2023-09-22-nested-formulas-and-advanced-functions
---

# Nested Formulas and Advanced Functions

Formulas can now be referenced within other formulas! Simplify complex expressions by creating named reusable intermediates.

Please reach out to our staff through Help and Support if you would like support in converting any existing formulas.

New functions are available in formulas to support timeseries evaluations.

**Timeseries Integration**

Function: `time_integral()`

Example: `Base Volume Totalizer = time_integral(base_volumetric_pump_rate)`

**Timeseries Derivative**

Function: `time_derivative_hours()`, `time_derivative_minutes()`,`time_derivative_seconds()`

Example: 
 `Acetate Accumulation Rate = time_derivative_hour(acetate_concentration)`

**Linear Regression**

Function: `linear_regression()`

Evaluation: `Y = mX+b`, where X = Elapsed Run Time

**Log-Linear Regression**

Function:`log_linear_regression()`

Evaluation: `ln(Y) = ln(b) + mX` or `Y = b*exp(mX)`, where X = Elapsed Run Time