[gcalctool/gcalctool-newui2] Stop modifying MP.t

[Robert Ancell <rancell src gnome org>]

commit 2bd7628b05a60fd4e8bab22810982248d8223515
Author: Robert Ancell <robert ancell gmail com>
Date:   Sat Jul 11 18:41:54 2009 +0800

    Stop modifying MP.t

 src/mp-trigonometric.c |   29 +++--------------------
 src/mp.c               |   59 +++++-------------------------------------------
 src/mp.h               |   14 ++++-------
 3 files changed, 15 insertions(+), 87 deletions(-)
---
diff --git a/src/mp-trigonometric.c b/src/mp-trigonometric.c
index 73c2ba2..a439ba5 100644
--- a/src/mp-trigonometric.c
+++ b/src/mp-trigonometric.c
@@ -90,19 +90,13 @@ mpsin1(const MPNumber *x, MPNumber *z, int do_sin)
         mp_set_from_integer(0, z);
 
     /* POWER SERIES LOOP.  REDUCE T IF POSSIBLE */
-    for (; ; i+= 2) {
-        int t, ts;
-        
-        t = MP.t + t1.exponent + 2;
-        if (t <= 2)
+    for (; ; i += 2) {
+        if (MP.t + t1.exponent <= 0)
             break;
-        t = min(t, MP.t);
 
         /*  IF I*(I+1) IS NOT REPRESENTABLE AS AN INTEGER, THE FOLLOWING
          *  DIVISION BY I*(I+1) HAS TO BE SPLIT UP.
          */
-        ts = MP.t;
-        MP.t = t;
         mp_multiply(&t2, &t1, &t1);
         if (i > b2) {
             mp_divide_integer(&t1, -i, &t1);
@@ -110,7 +104,6 @@ mpsin1(const MPNumber *x, MPNumber *z, int do_sin)
         } else {
             mp_divide_integer(&t1, -i * (i + 1), &t1);
         }
-        MP.t = ts;
         mp_add(&t1, z, z);
 
         if (t1.sign == 0)
@@ -154,18 +147,12 @@ mp_atan1N(int n, MPNumber *z)
 
     /* MAIN LOOP.  FIRST REDUCE T IF POSSIBLE */
     for (i = 1; ; i += 2) {
-        int t, ts;
-
-        t = MP.t + 2 + t2.exponent - z->exponent;
-        if (t <= 1)
+        if (MP.t + 2 + t2.exponent - z->exponent <= 1)
             break;
-        t = min(t, MP.t);
 
         /*  IF (I+2)*N**2 IS NOT REPRESENTABLE AS AN INTEGER THE DIVISION
          *  FOLLOWING HAS TO BE PERFORMED IN SEVERAL STEPS.
          */
-        ts = MP.t;
-        MP.t = t;
         if (i >= id) {
             mp_multiply_fraction(&t2, -i, i + 2, &t2);
             mp_divide_integer(&t2, n, &t2);
@@ -174,7 +161,6 @@ mp_atan1N(int n, MPNumber *z)
         else {
             mp_multiply_fraction(&t2, -i, (i + 2)*n*n, &t2);
         }
-        MP.t = ts;
 
         /* ADD TO SUM */
         mp_add(&t2, z, z);
@@ -545,18 +531,11 @@ mp_atan(const MPNumber *x, MPAngleUnit unit, MPNumber *z)
 
     /* SERIES LOOP.  REDUCE T IF POSSIBLE. */
     for (i = 1; ; i += 2) {
-        int t, ts;
-        
-        t = MP.t + 2 + t2.exponent;
-        if (t <= 1)
+        if (MP.t + 2 + t2.exponent <= 1)
             break;
-        t = min(t, MP.t);
         
-        ts = MP.t;
-        MP.t = t;
         mp_multiply(&t2, &t1, &t2);
         mp_multiply_fraction(&t2, -i, i + 2, &t2);
-        MP.t = ts;
 
         mp_add(z, &t2, z);
         if (t2.sign == 0)
diff --git a/src/mp.c b/src/mp.c
index c153a28..f2247c2 100644
--- a/src/mp.c
+++ b/src/mp.c
@@ -880,7 +880,7 @@ void
 mp_epowy(const MPNumber *x, MPNumber *z)
 {
     float r__1;
-    int i, ie, ix, ts, xs, tss;
+    int i, ie, ix, xs, tss;
     float rx, rz, rlb;
     MPNumber t1, t2;
 
@@ -951,32 +951,19 @@ mp_epowy(const MPNumber *x, MPNumber *z)
 
     t2.sign = 0;
     for (i = 2 ; ; i++) {
-        int t;
-        
-        t = min(tss, tss + 2 + t1.exponent);
-        if (t <= 2)
+        if (min(tss, tss + 2 + t1.exponent) <= 2)
             break;
         
-        ts = MP.t;
-        MP.t = t;
         mp_divide_integer(&t1, i * xs, &t1);
-        MP.t = ts;
-        
-        ts = MP.t;
-        MP.t = tss;
         mp_add(&t2, &t1, &t2);
-        MP.t = ts;
         if (t1.sign == 0)
             break;
     }
 
     /* RAISE E OR 1/E TO POWER IX */
-    ts = MP.t;
-    MP.t = tss;
     if (xs > 0)
         mp_add_integer(&t2, 2, &t2);
     mp_pwr_integer(&t2, ix, &t2);
-    MP.t = ts;
 
     /* MULTIPLY EXPS OF INTEGER AND FRACTIONAL PARTS */
     mp_multiply(z, &t2, z);
@@ -1079,18 +1066,11 @@ mpexp1(const MPNumber *x, MPNumber *z)
 
     /* SUM SERIES, REDUCING T WHERE POSSIBLE */
     for (i = 2; ; i++)  {
-        int t, ts;
-        
-        t = MP.t + 2 + t2.exponent - z->exponent;
-        if (t <= 2)
+        if (MP.t + t2.exponent - z->exponent <= 0)
             break;
-        t = min(t, MP.t);
 
-        ts = MP.t;
-        MP.t = t;
         mp_multiply(&t1, &t2, &t2);
         mp_divide_integer(&t2, i, &t2);
-        MP.t = ts;
 
         mp_add(&t2, z, z);
         if (t2.sign == 0)
@@ -1230,16 +1210,13 @@ mplns(const MPNumber *x, MPNumber *z)
 
         while(1)
         {
-            int ts, ts2, ts3;
+            int ts2, ts3;
             
-            ts = MP.t;
-            MP.t = t;
             mpexp1(z, &t3);
             mp_multiply(&t2, &t3, &t1);
             mp_add(&t3, &t1, &t3);
             mp_add(&t2, &t3, &t3);
             mp_subtract(z, &t3, z);
-            MP.t = ts;
             if (t >= MP.t)
                 break;
 
@@ -1890,24 +1867,12 @@ mp_reciprocal(const MPNumber *x, MPNumber *z)
     /* MAIN ITERATION LOOP */    
     if (t <= MP.t) {        
         while(1) {
-            int ts, ts2, ts3;
+            int ts2, ts3;
             
-            ts = MP.t;
-            MP.t = t;
             mp_multiply(x, &t1, &t2);
             mp_add_integer(&t2, -1, &t2);
-            MP.t = ts;
-
-            /* TEMPORARILY REDUCE T */
-            ts = MP.t;
-            MP.t = (t + it0) / 2;
             mp_multiply(&t1, &t2, &t2);
-            MP.t = ts;
-
-            ts = MP.t;
-            MP.t = t;
             mp_subtract(&t1, &t2, &t1);
-            MP.t = ts;
             if (t >= MP.t)
                 break;
 
@@ -2029,26 +1994,14 @@ mp_root(const MPNumber *x, int n, MPNumber *z)
 
         /* MAIN ITERATION LOOP */
         while(1) {
-            int ts, ts2, ts3;
+            int ts2, ts3;
 
-            ts = MP.t;
-            MP.t = t;
             mp_pwr_integer(&t1, np, &t2);
             mp_multiply(x, &t2, &t2);
             mp_add_integer(&t2, -1, &t2);
-            MP.t = ts;
-
-            /* TEMPORARILY REDUCE T */
-            ts = MP.t;
-            MP.t = (t + it0) / 2;
             mp_multiply(&t1, &t2, &t2);
             mp_divide_integer(&t2, np, &t2);
-            MP.t = ts;
-
-            ts = MP.t;
-            MP.t = t;
             mp_subtract(&t1, &t2, &t1);
-            MP.t = ts;
 
             /*  FOLLOWING LOOP ALMOST DOUBLES T (POSSIBLE BECAUSE
              *  NEWTONS METHOD HAS 2ND ORDER CONVERGENCE).
diff --git a/src/mp.h b/src/mp.h
index 2e8433f..a58a432 100644
--- a/src/mp.h
+++ b/src/mp.h
@@ -43,7 +43,10 @@
 /* Size of the multiple precision values */
 #define MP_SIZE 1000
 
-/* Object for a high precision floating point number representation */
+/* Object for a high precision floating point number representation
+ * 
+ * x = sign * (MP.b^(exponent-1) + MP.b^(exponent-2) + ...)
+ */
 typedef struct
 {
    /* Sign (+1, -1) or 0 for the value zero */
@@ -52,14 +55,7 @@ typedef struct
    /* Exponent (to base MP.b) */
    int exponent;
 
-   /* Normalized fraction
-    * 
-    * If exponent > 0, contains 'exponent' elements
-    * x = sign * (fraction[0]*MP.b^(exponent-1) + fraction[1]*MP.b^(exponent-2) + ...)
-    * 
-    * If exponent <= 0, contains 1-'exponent' elements
-    * x = sign * (... + fraction[0]*MP.b^(exponent-2) + fraction[1]*MP.b(^exponent-1))
-    */
+   /* Normalized fraction */
    int fraction[MP_SIZE];
 } MPNumber;