# C# Math: Sign Exp IEEERemainder, BigMul and DivRem

Use the Math type. This type offers many mathematical functions ready to deploy.
Math is a class in the System namespace. The .NET Framework provides many built-in mathematical methods. These are easier to use than custom expressions.
These methods are tested and easy to access. This page contains information on some less-common math methods like Sign and DivRem.
Sign. Is a number positive or negative? The Math.Sign method will help you determine this. Math.Sign accepts many numeric types as arguments. It returns one of three values: -1, 0 or 1.

Info: The result -1 means negative. Zero means the number is zero. And 1 means it is positive.

Next: This program demonstrates the Math.Sign method with ints and doubles as arguments.

C# program that uses Math.Sign method using System; class Program { static void Main() { int a = Math.Sign(-5); int b = Math.Sign(5); int c = Math.Sign(0); Console.WriteLine(a); Console.WriteLine(b); Console.WriteLine(c); a = Math.Sign(-5.5); b = Math.Sign(5.5); Console.WriteLine(a); Console.WriteLine(b); } } Output -1 1 0 -1 1
Sign, implementation. Sign is implemented with branch statements that test the parameter against zero. Sign returns 0 when the argument is 0—zero is neither positive nor negative.
Exp. Math.Exp is the exponential function. To apply the exponential function, we either use Math.Pow to raise E to a specified power, or call Math.Exp with the exponent as an argument.

Here: This program calls the Math.Exp method and then calls the Math.Pow method such that they have equivalent results.

Note: The Math.Exp always uses Math.E (e) as the specified number. The results of these two method calls are the same.

C# program that uses Exp method using System; class Program { static void Main() { // Compute e ^ 2. double a = Math.Exp(2); double b = Math.Pow(Math.E, 2); // Write results. Console.WriteLine(a); Console.WriteLine(b); } } Output 7.38905609893065 7.38905609893065
IEEERemainder. The IEEERemainder method returns a remainder of 1 for the arguments 4, 3. This is the same result as the modulo expression.

But: With the arguments 3 and 4, it returns a remainder of -1. The modulo expression meanwhile returns the value 3.

Here: We see that for IEEERemainder, two positive numbers can have a negative remainder.

Tip: This occurs when the first number is smaller than the second number. In many cases, the modulo operator returns the same result.

C# program that uses IEEERemainder using System; class Program { static void Main() { double a = Math.IEEERemainder(4, 3); Console.WriteLine("Part 1"); Console.WriteLine(a); Console.WriteLine(4 % 3); double b = Math.IEEERemainder(3, 4); Console.WriteLine("Part 2"); Console.WriteLine(b); Console.WriteLine(3 % 4); } } Output Part 1 1 1 Part 2 -1 3
BigMul. This multiplies two integers. With regular multiplication, as with the star operator, the result may overflow. BigMul avoids this problem. It returns a long.

Here: This program's goal is to multiply the int.MaxValue value (2147483647) by itself. If we call Math.BigMul, the result will be correct.

C# program that calls BigMul using System; class Program { static void Main() { // Call BigMul. long product1 = Math.BigMul(int.MaxValue, int.MaxValue); // Use multiplication operator. long product2 = unchecked(int.MaxValue * int.MaxValue); // Display values. Console.WriteLine(product1); Console.WriteLine(product2); } } Output 4611686014132420609 1
BigMul, notes. When you multiply two large numbers like 2147483647 you should not get 1. This makes no sense. Instead, you should get a larger number.

Note: If you query Google for 2147483647 squared, it will give you the correct result.

So: You should probably use BigMul anywhere you are multiplying large integers.

MultiplyOverflowExceptionInt, uint
DivRem. Math.DivRem divides two numbers and returns the remainder. With the division operator we do not get the remainder in a separate variable. But with DivRem we get both parts.

Here: This program divides the value 1000 by the value 300. Because the 300 can go into the 1000 three times, you get the result of 3.

However: There is 100 left over. This is returned by the out parameter in the Math.DivRem method.

Tip: The out parameter in the DivRem method is always assigned when DivRem returns. It will be ready to use.

Out
C# program that calls DivRem method using System; class Program { static void Main() { const int a = 1000; const int b = 300; int result; int quotient = Math.DivRem(a, b, out result); Console.WriteLine(quotient); Console.WriteLine(result); } } Output 3 100
A summary. Instead of implementing these functions yourself, I suggest using the Math type. It has many public static methods. You may be able to improve the quality of your code.
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