Function to calculate the square root of a number

modules/maths/square_root_module.f90

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+!> Module containing functions related to square root calculation.
+!!
+!!  Created by: ITZ-NIHALPATEL
+!!
+!!  This module provides a function to calculate the square root of a number
+!!  using Fortran's intrinsic SQRT function.
+!!
+module square_root_module
+    implicit none
+    private ! Default module entities to private
+
+    public :: calculate_sqrt ! Make the function public
+
+contains
+
+    !> Calculates the square root of a non-negative number.
+    !! Uses the intrinsic SQRT function.
+    !!
+    !! @param number The number (real) for which to calculate the square root.
+    !!               Must be non-negative.
+    !! @return The square root of the number (real). Returns -1.0 for negative input.
+    function calculate_sqrt(number) result(sqrt_val)
+        real, intent(in) :: number
+        real :: sqrt_val
+
+        if (number < 0.0) then
+            print *, "Error: Input to calculate_sqrt must be non-negative."
+            sqrt_val = -1.0 ! Indicate error for negative input
+        else
+            sqrt_val = sqrt(number) ! Use Fortran's intrinsic sqrt function
+        end if
+    end function calculate_sqrt
+
+end module square_root_module

modules/maths/tests_square_root.f90

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+!> Test program for the square root function.
+!!
+!!  Created by: ITZ-NIHALPATEL
+!!
+!!  This program provides test cases to validate the square root function
+!!  in the square_root_module.
+
+program tests_square_root
+    use square_root_module
+    implicit none
+
+    real :: result, expected
+    real, parameter :: tolerance = 1e-6 ! Tolerance for floating-point comparison
+
+    ! Run test cases
+    call test_sqrt_zero()
+    call test_sqrt_one()
+    call test_sqrt_perfect_square()
+    call test_sqrt_non_perfect_square()
+    call test_sqrt_large_number()
+    call test_sqrt_negative_input()
+
+    print *, "All square root tests completed."
+
+contains
+
+    ! Test case 1: Square root of 0
+    subroutine test_sqrt_zero()
+        expected = 0.0
+        result = calculate_sqrt(0.0)
+        call assert_test(result, expected, "Test 1: Square root of 0", tolerance)
+    end subroutine test_sqrt_zero
+
+    ! Test case 2: Square root of 1
+    subroutine test_sqrt_one()
+        expected = 1.0
+        result = calculate_sqrt(1.0)
+        call assert_test(result, expected, "Test 2: Square root of 1", tolerance)
+    end subroutine test_sqrt_one
+
+    ! Test case 3: Square root of a perfect square (e.g., 16)
+    subroutine test_sqrt_perfect_square()
+        expected = 4.0
+        result = calculate_sqrt(16.0)
+        call assert_test(result, expected, "Test 3: Square root of 16", tolerance)
+    end subroutine test_sqrt_perfect_square
+
+    ! Test case 4: Square root of a non-perfect square (e.g., 2)
+    subroutine test_sqrt_non_perfect_square()
+        expected = 1.41421356
+        result = calculate_sqrt(2.0)
+        call assert_test(result, expected, "Test 4: Square root of 2", tolerance)
+    end subroutine test_sqrt_non_perfect_square
+
+    ! Test case 5: Square root of a larger number (e.g., 12345.0)
+    subroutine test_sqrt_large_number()
+        expected = 111.108055
+        result = calculate_sqrt(12345.0)
+        call assert_test(result, expected, "Test 5: Square root of 12345.0", tolerance)
+    end subroutine test_sqrt_large_number
+
+    ! Test case 6: Square root of a negative number
+    subroutine test_sqrt_negative_input()
+        expected = -1.0 ! Expected error indicator
+        result = calculate_sqrt(-9.0)
+        call assert_test(result, expected, "Test 6: Square root of -9 (Negative Input)", tolerance)
+    end subroutine test_sqrt_negative_input
+
+    !> Subroutine to assert the test results for real numbers
+    !! Includes a tolerance for floating-point comparisons.
+    subroutine assert_test(actual, expected, test_name, tol)
+        real, intent(in) :: actual, expected, tol
+        character(len=*), intent(in) :: test_name
+
+        if (abs(actual - expected) <= tol) then
+            print *, test_name, " PASSED"
+        else
+            print *, test_name, " FAILED"
+            print *, "Expected: ", expected
+            print *, "Got: ", actual
+            stop 1 ! Stop execution on failure
+        end if
+
+    end subroutine assert_test
+
+end program tests_square_root