refactoring: split function logN in smaller subfunctions

src/exponent.c

@@ -37,13 +37,13 @@ double powerD(double exp, double base){
         }   
     }else if(base > 0.0){
         if(exp>=0.0){
-            return exponential(exp*logN(base, 0.00000001));
+            return exponential(exp*logN(base));
         }
         else{
             if (base == 0.0){
                 return -1.0;
             }
-            return (1.0 / exponential((-1*exp)*logN(base, 0.00000001)));
+            return (1.0 / exponential((-1*exp)*logN(base)));
         }
     }
     return -1.0;

src/logarithmus.c

@@ -8,7 +8,7 @@ double logX(double base, double value){
     if(base == 1.0 || base <= 0.0 || value <= 0.0){
         return -1.0;
     }
-    return(logN(value, 0.00000001)/logN(base, 0.00000001));
+    return(logN(value)/logN(base));
 }
 
 double log10(double value){
@@ -18,41 +18,48 @@ double log10(double value){
 double log2(double value){
     return logX(2.0, value);
 }
+double lns(double x, double eps){
+    double yn = x - 1.0;
+    double yn1 = yn;
 
-double logN(double x, double eps){
+    do{
+        yn = yn1;
+        yn1 = yn + 2 * (x - exponential(yn)) / (x + exponential(yn));
+    } while (absD(yn - yn1) > eps);
+
+    return yn1;
+}
+
+double lnb(double x){
+    int power_adjust = 0;
+    while (x > 1.0) {
+        x /= exponential(1);
+        power_adjust++;
+    }
+    while (x < .25) {
+        x *= exponential(1);
+        power_adjust--;
+    }
+    
+    x -= 1.0;
+    double t = 0.0, s = 1.0, z = x;
+    for (int k=1; k<=100; k++) {
+        t += z * s / k;
+        z *= x;
+        s = -s;
+    }
+    return t + power_adjust;   
+}
+
+double logN(double x){
     if(x <= 0){
         return -1.0;
     }
     if(x<200){
-        double yn = x - 1.0;
-        double yn1 = yn;
-
-        do{
-            yn = yn1;
-            yn1 = yn + 2 * (x - exponential(yn)) / (x + exponential(yn));
-        } while (absD(yn - yn1) > eps);
-
-        return yn1;
+        return lns(x, 0.00000001);
     }
     else{
-        int power_adjust = 0;
-        while (x > 1.0) {
-            x /= exponential(1);
-            power_adjust++;
-        }
-        while (x < .25) {
-            x *= exponential(1);
-            power_adjust--;
-        }
-        
-        x -= 1.0;
-        double t = 0.0, s = 1.0, z = x;
-        for (int k=1; k<=100; k++) {
-            t += z * s / k;
-            z *= x;
-            s = -s;
-        }
-        return t + power_adjust;
+        return lnb(x);
     }    
 }
 

src/logarithmus.h

@@ -1,7 +1,7 @@
 #ifndef LOGARITHMUS_H
 #define LOGARITHMUS_H
 
-double logN(double x, double eps);
+double logN(double x);
 double logX(double b, double a);
 double log10(double a);
 double log2(double a);

test/test_logarithmus.c

@@ -16,9 +16,9 @@ void tearDown(void)
 void test_ln_with_positive_number(void){
     double r1, r2, r3;
 
-    r1 = logN(1.0, 0.000001);
-    r2 = logN(10.0, 0.000001);
-    r3 = logN(2.5, 0.000001);
+    r1 = logN(1.0);
+    r2 = logN(10.0);
+    r3 = logN(2.5);
 
     TEST_ASSERT_DOUBLE_WITHIN(0.000001, 0, r1);
     TEST_ASSERT_DOUBLE_WITHIN(0.000001, 2.302585, r2);
@@ -28,9 +28,9 @@ void test_ln_with_positive_number(void){
 void test_ln_with_zero_and_negative_numbers(void){
     double r1, r2, r3;
 
-    r1 = logN(0.0, 0.000001);
-    r2 = logN(-1.0, 0.000001);
-    r3 = logN(-2.5, 0.000001);
+    r1 = logN(0.0);
+    r2 = logN(-1.0);
+    r3 = logN(-2.5);
 
     TEST_ASSERT_EQUAL_DOUBLE(-1.0, r1);
     TEST_ASSERT_EQUAL_DOUBLE(-1.0, r2);