### Course Objectives

Introduction to Calculus

### Course Outlines

Introduction to Calculus

### Outcome

Introduction to Calculus

### Target Audience

Introduction to Calculus

**Calculus** (from Latin *calculus*, literally ‘small pebble’, used for counting and calculations, like on an abacus)^{[1]} is the mathematical study of continuous change, in the same way that geometry is the study of shape and algebra is the study of generalizations of arithmetic operations. It has two major branches, differential calculus (concerning rates of change and slopes of curves),^{[2]} and integral calculus (concerning accumulation of quantities and the areas under and between curves).^{[3]} These two branches are related to each other by the fundamental theorem of calculus. Both branches make use of the fundamental notions of convergence of infinite sequences and infinite seriesto a well-defined limit. Generally, modern calculus is considered to have been developed in the 17th century by Isaac Newton and Gottfried Wilhelm Leibniz. Today, calculus has widespread uses in science, engineering, and economics.^{[4]}

Calculus is a part of modern mathematics education. A course in calculus is a gateway to other, more advanced courses in mathematics devoted to the study of functions and limits, broadly called mathematical analysis. Calculus has historically been called “the calculus of infinitesimals“, or “infinitesimal calculus”. The term *calculus* (plural *calculi*) is also used for naming specific methods of calculation or notation as well as some theories, such as propositional calculus, Ricci calculus, calculus of variations, lambda calculus, and process calculus.

## Principles

### Limits and infinitesimals

Calculus is usually developed by working with very small quantities. Historically, the first method of doing so was by infinitesimals. These are objects which can be treated like real numbers but which are, in some sense, “infinitely small”. For example, an infinitesimal number could be greater than 0, but less than any number in the sequence 1, 1/2, 1/3, … and thus less than any positive real number. From this point of view, calculus is a collection of techniques for manipulating infinitesimals. The symbols *dx* and *dy* were taken to be infinitesimal, and the derivative {displaystyle dy/dx} was simply their ratio.

The infinitesimal approach fell out of favor in the 19th century because it was difficult to make the notion of an infinitesimal precise. However, the concept was revived in the 20th century with the introduction of non-standard analysis and smooth infinitesimal analysis, which provided solid foundations for the manipulation of infinitesimals.

In the 19th century, infinitesimals were replaced by the epsilon, delta approach to limits. Limits describe the value of a function at a certain input in terms of its values at a nearby input. They capture small-scale behavior in the context of the real number system. In this treatment, calculus is a collection of techniques for manipulating certain limits. Infinitesimals get replaced by very small numbers, and the infinitely small behavior of the function is found by taking the limiting behavior for smaller and smaller numbers. Limits were the first way to provide rigorous foundations for calculus, and for this reason they are the standard approach.

### Differential calculus

Differential calculus is the study of the definition, properties, and applications of the derivative of a function. The process of finding the derivative is called *differentiation*. Given a function and a point in the domain, the derivative at that point is a way of encoding the small-scale behavior of the function near that point. By finding the derivative of a function at every point in its domain, it is possible to produce a new function, called the *derivative function* or just the *derivative* of the original function. In formal terms, the derivative is a linear operator which takes a function as its input and produces a second function as its output. This is more abstract than many of the processes studied in elementary algebra, where functions usually input a number and output another number. For example, if the doubling function is given the input three, then it outputs six, and if the squaring function is given the input three, then it outputs nine. The derivative, however, can take the squaring function as an input. This means that the derivative takes all the information of the squaring function—such as that two is sent to four, three is sent to nine, four is sent to sixteen, and so on—and uses this information to produce another function. The function produced by deriving the squaring function turns out to be the doubling function.

In more explicit terms the “doubling function” may be denoted by *g*(*x*) = 2*x* and the “squaring function” by *f*(*x*) = *x*^{2}. The “derivative” now takes the function *f*(*x*), defined by the expression “*x*^{2}“, as an input, that is all the information —such as that two is sent to four, three is sent to nine, four is sent to sixteen, and so on— and uses this information to output another function, the function *g*(*x*) = 2*x*, as will turn out.

The most common symbol for a derivative is an apostrophe-like mark called prime. Thus, the derivative of a function called *f* is denoted by *f′*, pronounced “f prime”. For instance, if *f*(*x*) = *x*^{2} is the squaring function, then *f′*(*x*) = 2*x* is its derivative (the doubling function *g* from above). This notation is known as Lagrange’s notation.

If the input of the function represents time, then the derivative represents change with respect to time. For example, if *f* is a function that takes a time as input and gives the position of a ball at that time as output, then the derivative of *f* is how the position is changing in time, that is, it is the velocity of the ball.

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