Exercise 4.4 Did I get it?

[JackRabbit]

Greetings everyone.

Here is my answer for Exercise 4.

Code: (Objective-C)

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[])
    {

        @autoreleasepool
            {
                float x = 2.55;
                float total;
                
                total = 3 * (x * x * x) - 5 * (x * x) + 6;
                
                NSLog (@"3 * (x * x * x) - 5 * (x * x) + 6 = %g", total);
            }
        
        return 0;
    }

Out put:

 3 * (x * x * x) - 5 * (x * x) + 6 = 23.2316

Well, did I get it?

JR

[rue]

I think so, I just got the same answer too.

Code: (Objective-C)

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[])
{

    @autoreleasepool {
        
        // evaluate 3x^3 - 5x^2 + 6 for x=2.55
        
        double x,answer;
        
        x = 2.55;
        
        answer = 3*(x*x*x) - (5*(x*x)) + 6 ;
        
        NSLog(@"Answer is %g",answer);
        
    }
    return 0;
}

Answer is 23.2316

[JackRabbit]

Hello rue!

What a relief! I hate this math stuff. But I better learn to love it! OK. On to Exercise 4.5.

And thank you for your feedback.

JR

[clouded]

Here's my solution pretty similar:

/

Code: (Objective-C)

/ Chapter 4 Exercise 4.
// Write a program to evaluate the polynomial shown here
// (to calculate the exponents, just do straight
// multiplication — there is no exponentiation operator
// in Objective-C):
//              3x^3 - 5x^2 + 6
//              for x = 2.55

#include <Foundation/Foundation.h>

int main(int argc, const char *argv[]) {
    
    @autoreleasepool {
        double eval, x = 2.55;
        eval = (3 * (x * x * x)) - (5 * (x * x)) + 6;
        NSLog(@"3x^3 - 5x^2 + 6; for x = 2.55 equals %f", eval);
    }
    return 0;
}

[Sequals3]

I might have cheated on this one, because I used the math.h class that looks to be included in Foundation.h when it's imported.  Here is my code and solution.  What you guys have is correct though.

Code: (Objective-C)

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[])
{

    @autoreleasepool {
        double x = 2.55, result = 3*(pow(x, 3))-5*(pow(x, 2))+6;
        NSLog(@"3x^3 - 5x^2 + 6 = %g", result);
    }
    return 0;
}