# COSINTEGRAL function

## Description

COSINTEGRAL(x) returns the value of the cosine integral function of x. The cosine integral function is defined as:

$$ {\rm Ci}(x) = \gamma + \ln x + \int_0^x\frac{\cos t-1}{t}\,dt $$

where γ = 0.57721566490153 (Euler-Mascheroni constant).

The argument x can be a real number or a matrix. When it is a matrix, the function returns a matrix with the same dimensions and with the COSINTEGRAL function applied to all elements.

## Calculator

## Graph

## Related functions

## External links

## Recommended book

## Trigonometry: A Complete Introduction

Hugh Neill

Buy from Amazon

This book covers all areas of trigonometry including the theory and equations of tangent, sine and cosine, using trigonometry in three dimensions and for angles for any magnitude, related to triangles. Everything you will need is here in this one book. Each chapter includes not only an explanation of the knowledge and skills you need, but also worked examples and test questions.