How to express an imaginary number in method argument in Objective-C - objective-c

Question

"nan" and "nani" is being displayed in my output. I have discovered that this stands for "not a number", but I am not able to see where I am going wrong, and whether my problem lies with my lack of understanding of Objective-C, or imaginary numbers, or something else.
Any help or pointers would be much appreciated!
Thanks.
#import <Foundation/Foundation.h>
#interface Complex: NSNumber
-(void) setReal: (double) a;
-(void) setImaginary: (double) b;
-(void) print; // display as a + bi
-(double) real;
-(double) imaginary;
#end
#implementation Complex
{
double real;
double imaginary;
}
-(void) setReal: (double) a
{
real = a;
}
-(void) setImaginary: (double) b
{
imaginary = b;
}
-(void) print
{
NSLog (#"%f x %fi = %f", real, imaginary, real * imaginary);
}
-(double) real
{
return real;
}
-(double) imaginary
{
return imaginary;
}
#end
int main (int argc, const char * argv[])
{
#autoreleasepool {
Complex *complex1 = [[Complex alloc] init];
// Set real and imaginary values for first complex sum:
[complex1 setReal: 2];
[complex1 setImaginary: 3 * (sqrt(-1))];
// Display first complex number sum with print method:
NSLog (#"When a = 2 and b = 3, the following equation a x bi =");
[complex1 print];
//Display first complex number sum with getter method:
NSLog (#"When a = 2 and b = 3, the following equation
a x bi = %f x %fi = %fi", [complex1 real], [complex1 imaginary],
[complex1 real] * [complex1 imaginary]);
}
return 0;
}

Answer 1

Your NaNs come from sqrt(-1).
Do you want to implement your own complex types? C99 adds them, so unless you're using an ancient Objective-C compiler you'll be able to do something like this:
#include <complex.h>
double complex c = 3 * 2 I;
double r = creal(c);
double i = cimag(c);
There's some useful documentation and examples in the GNU libc manual: Complex Numbers.

Answer 2

The main problem is here:
[complex1 setImaginary: 3 * (sqrt(-1))];
The result of sqrt(-1) is NaN, sqrt() does not return "complex" numbers in any sense.
To set the imaginary part of your Complex object, you just set
[complex1 setImaginary: 3];
(setImaginary: expects a double argument, which makes sense because the imaginary part of a complex number is a real number.)
Remark: I have no idea what you want to achieve with your print method, but it does not
print a + bi as stated at the top of your program.