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Math Type
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Math. This is a class in the System namespace. The .NET Framework provides many built-in mathematical methods. These are easier to use than custom expressions.
Math methods. These methods are tested and easy to access. This page contains information on some less-common math methods like Sign and DivRem.
Math.Round
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.
Tip Sign is implemented with branch statements that test the parameter against zero.
using System; 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);
-1 1 0 -1 1
Log. Here we compute the logarithms of some known numbers. The logarithm of 1 with base "e" is always zero—the method matches this result.
And The logarithm of 1000 with base 10 is always 3. This is because 10 to the power of 3 is 1000.
Math.Pow
Finally You can duplicate the effects of Log10 with Log by passing 10 as the second argument.
using System; double a = Math.Log(1); Console.WriteLine(a); // Ten to the power of 3 is 1000. double b = Math.Log10(1000); Console.WriteLine(b); double c = Math.Log(1000, 10); Console.WriteLine(c);
0 3 3
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.
using System; // Compute e ^ 2. double a = Math.Exp(2); double b = Math.Pow(Math.E, 2); // Write results. Console.WriteLine(a); Console.WriteLine(b);
7.38905609893065 7.38905609893065
IEEERemainder. This is similar to a modulo expression, but the results are different when we use a larger second number. In many cases, the modulo operator returns the same result.
Part 1 The IEEERemainder method returns a remainder of 1 for the arguments 4, 3. This is the same result as the modulo expression.
Part 2 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.
using System; // Part 1: use larger first number. double a = Math.IEEERemainder(4, 3); Console.WriteLine("Part 1"); Console.WriteLine(a); Console.WriteLine(4 % 3); // Part 2: use smaller first number. double b = Math.IEEERemainder(3, 4); Console.WriteLine("Part 2"); Console.WriteLine(b); Console.WriteLine(3 % 4);
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.
Tip You should probably use BigMul anywhere you are multiplying large integers.
Multiply
OverflowException
int, uint
using System; // 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);
4611686014132420609 1
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
using System; const int a = 1000; const int b = 300; int result; int quotient = Math.DivRem(a, b, out result); Console.WriteLine(quotient); Console.WriteLine(result);
3 100
E constant. To access Math.E, use "System.Math.E" or include the using System directive at the top. The constant is encoded as a Float64 type in the Framework. Float64 has a 64-bit data space.
double
using System; double e = Math.E; // Get E constant Console.WriteLine("--- Math.E ---"); Console.WriteLine(e); // Write E constant
--- Math.E --- 2.71828182845905
Cos, sin, tan. This example calls Acos, Cos, Cosh, Asin, Sin, Sinh, Atan, Tan and Tanh. All of these methods receive arguments in units of radians represented by the double type.
Next In this program, the C# compiler implicitly converts the integer arguments into double arguments.
using System; Console.WriteLine(Math.Acos(0)); // Inverse cosine Console.WriteLine(Math.Cos(2)); // Cosine Console.WriteLine(Math.Cosh(5)); // Hyperbolic cosine Console.WriteLine(Math.Asin(0.2)); // Inverse sine Console.WriteLine(Math.Sin(2)); // Sine Console.WriteLine(Math.Sinh(-5)); // Hyperbolic sine Console.WriteLine(Math.Atan(-5)); // Inverse tangent Console.WriteLine(Math.Tan(1)); // Tangent Console.WriteLine(Math.Tanh(0.1)); // Hyperbolic tangent
1.5707963267949 -0.416146836547142 74.2099485247878 0.201357920790331 0.909297426825682 -74.2032105777888 -1.37340076694502 1.5574077246549 0.0996679946249558
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.
Dot Net Perls is a collection of tested code examples. Pages are continually updated to stay current, with code correctness a top priority.
Sam Allen is passionate about computer languages. In the past, his work has been recommended by Apple and Microsoft and he has studied computers at a selective university in the United States.