Objective-C applies to C mathematical functions

Reprinted: http://hi.baidu.com/delphi9527/blog/item/2f29650d1302f2306159f319.html

 

In actual workProgramIt is inevitable to use mathematical functions for calculation, such as the transformation from the geographic coordinates of the map program to the map coordinates. As an extension of ansi c, objective-C uses the C standard library header file <math. h> mathematical constant macros and mathematical functions defined in to implement basic mathematical computation operations, so you don't have to bother looking for corresponding functions and classes in the cocoa Foundation. Some common macros and mathematical functions are listed here. For more details, refer to the header file <math. h>.

Mathematical constants:
# Define m_e 2.71828182845904523536028747135266250 // E
# Define m_log2e 1.44269504088896340735992468100189214 // log 2e
# Define m_log10e 0.434294481903251827651128918916605082 // log 10E
# Define m_ln2 0.693147180559945309417232121458176568 // log E2
# Define m_ln10 2.30258509299404568401799145468436421 // log E10
# Define m_pi 3.14159265358979323846264338327950288 // pi
# Define m_pi_2 1.57079632679489661923132169163975144 // PI/2
# Define m_pi_4 0.785398163397448309615660845819875721 // PI/4
# Define m_0000pi 0.318309886183790671537767526745028724 // 1/PI
# Define m_2_pi 0.636619772367581343075535053490057448 // 2/PI
# Define m_2_sqrtpi 1.12837916709551257389615890312154517 // 2/SQRT (PI)
# Define m_sqrt2 1.41421356237309504880168872420969808 // SQRT (2)
# Define m_sqrt1_2 0.707106781186547524400844362104849039 // 1/SQRT (2)

Common functions:
// Exponential operation
Nslog (@ "%. F", POW (3, 2); // result 9
Nslog (@ "%. F", POW (3, 3); // result 27

// Square operation
Nslog (@ "%. F", SQRT (16); // Result 4
Nslog (@ "%. F", SQRT (81); // result 9

// Rounding up
Nslog (@ "res: %. F", Ceil (3.000000000001); // Result 4
Nslog (@ "res: %. F", Ceil (3.00); // result 3

// Drop-down
Nslog (@ "res: %. F", floor (3.000000000001); // result 3
Nslog (@ "res: %. F", floor (3.9999999); // result 3

// Rounding
Nslog (@ "res: %. F", round (3.5); // Result 4
Nslog (@ "res: %. F", round (3.46); // result 3
Nslog (@ "res: %. F", round (-3.5); // NB: This one returns-4

// Minimum value
Nslog (@ "res: %. F", fmin (5, 10); // result 5

// Maximum value
Nslog (@ "res: %. F", fmax (5, 10); // result 10

// Absolute value Nslog (@ "res: %. F", FABS (10); // result 10 Nslog (@ "res: %. F", FABS (-10); // result 10 The trigonometric functions not listed here are also part of the C standard mathematical functions, which can also be viewed in <math. h>.