PART A · PRESCRIBED EXERCISE 03

Demonstrate six math.h functions

Understand the algorithm. Run the code.
Explain the result with confidence.

Aim & definitionStep-by-step algorithmWorked sampleExtra test cases3 viva answers

LAB A03 · 01

Understand the task.

Aim: Demonstrate six math.h functions.

DEFINITION

Mathematical library. math.h declares standard C mathematical functions. Their floating-point arguments and results support operations such as square root, powers, rounding and logarithms.

Review the related theory in Unit 1.

LAB A03 · 02

Know what goes in and what comes out.

One positive number x, greater than 0 and at most 100. This shared range keeps all six demonstrated operations in their intended domains.

Sample input

2.5

Expected output

sqrt = 1.58
pow(x, 2) = 6.25
ceil = 3.00
floor = 2.00
fabs(-x) = 2.50
log = 0.92

Source programs read the documented input directly, without prompt text, so the same sample works in the embedded compiler’s STDIN field.

LAB A03 · 03

Plan the steps before writing code.

Read x as double and validate 0 < x <= 100.
Evaluate sqrt(x) and pow(x, 2.0).
Evaluate ceil(x), floor(x) and fabs(-x).
Evaluate log(x), the natural logarithm.
Display each result to two decimal places.

LAB A03 · 04

One complete program. Ready to run.

Demonstrate six math.h functionsmain.c

#include <stdio.h>
#include <math.h>
int main(void)
{
    double x;
    if (scanf("%lf", &x) != 1 || !(x > 0.0 && x <= 100.0)) {
        puts("Enter a positive value up to 100.");
        return 1;
    }
    printf("sqrt = %.2f\n", sqrt(x));
    printf("pow(x, 2) = %.2f\n", pow(x, 2.0));
    printf("ceil = %.2f\n", ceil(x));
    printf("floor = %.2f\n", floor(x));
    printf("fabs(-x) = %.2f\n", fabs(-x));
    printf("log = %.2f\n", log(x));
    return 0;
}

EXPECTED OUTPUT

sqrt = 1.58
pow(x, 2) = 6.25
ceil = 3.00
floor = 2.00
fabs(-x) = 2.50
log = 0.92

Try this program Download A03-math-functions.c

Compile on your own computer

gcc A03-math-functions.c -o program -lm

Run the generated program and enter the sample input. The examples use standard C90-compatible syntax and explicit function declarations. For these learning programs, enter numeric values representable in the stated C types and within the documented ranges.

LAB A03 · 05

Connect each statement to its purpose.

sqrt finds the nonnegative square root; pow computes a power.
ceil rounds toward positive infinity, while floor rounds toward negative infinity. Both return floating-point values.
fabs computes floating-point absolute value; integer abs belongs to stdlib.h.
log means the natural logarithm, base e. log10 is a different function.
Include math.h for declarations. For a GCC command-line build, put -lm after the source/object file to link the mathematics library on systems that require it.

LAB A03 · 06

Follow the sample calculation.

Step or component	What happens
sqrt(2.5)	≈ 1.58
pow(2.5, 2.0)	6.25
ceil / floor	3.00 / 2.00
fabs(-2.5)	2.50
log(2.5)	≈ 0.92

LAB A03 · 07

Check more than one input.

Try this input or case	Expected behaviour
1	Square root 1, square 1, natural log 0.
4	Square root 2, square 16.
0, negative, NaN or text	Rejected by the shared positive-input rule.

Time and storage

A fixed six library calls; operation count is independent of the amount of input. Internal library algorithms are implementation-dependent.

Start with the sample, then test a boundary and a case that changes the result. A correct sample alone does not establish that every input is handled correctly.

LAB A03 · 08

Use the real C compiler.

Choose an example and load it into the embedded C compiler. Select I/O inside the compiler, check the sample STDIN, and press Run. Change the input or edit the source to explore a different case.

Example program

Sample input (STDIN)

2.5

Expected output

sqrt = 1.58
pow(x, 2) = 6.25
ceil = 3.00
floor = 2.00
fabs(-x) = 2.50
log = 0.92

Load the compiler when you’re ready to practise.

Your C workspace

Edit real C code and see real compiler output.

Compiler provided by OneCompiler. Opening the editor connects to that service; code and input you run are processed there. If the embed is unavailable, open the C compiler in a new tab and paste the source below.

View / copy the selected source

#include <stdio.h>
#include <math.h>
int main(void)
{
    double x;
    if (scanf("%lf", &x) != 1 || !(x > 0.0 && x <= 100.0)) {
        puts("Enter a positive value up to 100.");
        return 1;
    }
    printf("sqrt = %.2f\n", sqrt(x));
    printf("pow(x, 2) = %.2f\n", pow(x, 2.0));
    printf("ceil = %.2f\n", ceil(x));
    printf("floor = %.2f\n", floor(x));
    printf("fabs(-x) = %.2f\n", fabs(-x));
    printf("log = %.2f\n", log(x));
    return 0;
}

LAB A03 · 09

Explain why the program works.

Does ceil return int?

No. The ceil function used here returns double. Formatting it with %.2f is valid.

Why reject zero although sqrt(0) is valid?

This same input is also passed to log, whose intended finite real-valued domain here is positive numbers.

Is pow(x, 2.0) the same as x ^ 2?

No. In C, ^ is the bitwise XOR operator, not exponentiation.

LAB A03 · 10

Build the next skill.

Read the viva answers, try the extra cases, and return to the lab index to mark this exercise as practised.

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