Index: source/blender/src/drawnode.c
===================================================================
--- source/blender/src/drawnode.c	(revision 17197)
+++ source/blender/src/drawnode.c	(working copy)
@@ -521,7 +521,7 @@
 	if(block) { 
 		uiBut *bt; 
 
-		bt=uiDefButS(block, MENU, B_NODE_EXEC,  "Add %x0|Subtract %x1|Multiply %x2|Divide %x3|Sine %x4|Cosine %x5|Tangent %x6|Arcsine %x7|Arccosine %x8|Arctangent %x9|Power %x10|Logarithm %x11|Minimum %x12|Maximum %x13|Round %x14|Less Than %x15|Greater Than %x16", butr->xmin, butr->ymin, butr->xmax-butr->xmin, 20, &node->custom1, 0, 0, 0, 0, ""); 
+		bt=uiDefButS(block, MENU, B_NODE_EXEC,  "Add %x0|Subtract %x1|Multiply %x2|Divide %x3|Sine %x4|Cosine %x5|Tangent %x6|Arcsine %x7|Arccosine %x8|Arctangent %x9|Sqrt %x10|Power %x11|Logarithm %x12|Minimum %x13|Maximum %x14|Round %x15|Less Than %x16|Greater Than %x17", butr->xmin, butr->ymin, butr->xmax-butr->xmin, 20, &node->custom1, 0, 0, 0, 0, ""); 
 		uiButSetFunc(bt, node_but_title_cb, node, bt); 
 	} 
 	return 20; 
Index: source/blender/nodes/intern/CMP_nodes/CMP_math.c
===================================================================
--- source/blender/nodes/intern/CMP_nodes/CMP_math.c	(revision 17197)
+++ source/blender/nodes/intern/CMP_nodes/CMP_math.c	(working copy)
@@ -28,6 +28,7 @@
  */
 
 #include "../CMP_util.h"
+#include <math.h>
 
 
 /* **************** SCALAR MATH ******************** */ 
@@ -42,113 +43,119 @@
 	{ -1, 0, "" } 
 };
 
-static void do_math(bNode *node, float *out, float *in, float *in2)
+static void do_math(bNode *node, float *out, float *in0, float *in1)
 {
+	float x = *in0;
+	float y = *in1;
+	float result = 0.0;
+
+	/* functions as sinf(float) are C99 conform and should be well supported */
 	switch(node->custom1)
 	{
 	case 0: /* Add */
-		out[0]= in[0] + in2[0]; 
+		result = x+y;
 		break; 
 	case 1: /* Subtract */
-		out[0]= in[0] - in2[0];
+		result = x-y;
 		break; 
 	case 2: /* Multiply */
-		out[0]= in[0] * in2[0]; 
+		result = x*y;
 		break; 
 	case 3: /* Divide */
 		{
-			if(in2[0]==0)	/* We don't want to divide by zero. */
-				out[0]= 0.0;
+			if (y==0)	   /* We don't want to divide by zero. */
+				result = 0;
 			else
-				out[0]= in[0] / in2[0];
-			}
-		break;
+				result = x/y;
+		} break;
 	case 4: /* Sine */
-		out[0]= sin(in[0]);
+		result = sinf(x);
 		break;
 	case 5: /* Cosine */
-		out[0]= cos(in[0]);
+		result = cosf(x);
 		break;
 	case 6: /* Tangent */
-		out[0]= tan(in[0]);
+		result = tanf(x);
 		break;
 	case 7: /* Arc-Sine */
 		{
 			/* Can't do the impossible... */
-			if(in[0] <= 1 && in[0] >= -1 )
-				out[0]= asin(in[0]);
+			if (x <= 1 && x >= -1 )
+				result = asinf(x);
 			else
-				out[0]= 0.0;
-		}
-		break;
+				result = 0;
+		} break;
 	case 8: /* Arc-Cosine */
 		{
 			/* Can't do the impossible... */
-			if( in[0] <= 1 && in[0] >= -1 )
-				out[0]= acos(in[0]);
+			if( x <= 1 && x >= -1 )
+				result = acosf(x);
 			else
-				out[0]= 0.0;
-		}
-		break;
+				result = 0;
+		} break;
 	case 9: /* Arc-Tangent */
-		out[0]= atan(in[0]);
+		result = atanf(x);
 		break;
-	case 10: /* Power */
+	case 10: /* SQRT, sqrt(x) */
 		{
-			/* Don't want any imaginary numbers... */
-			if( in[0] >= 0 )
-				out[0]= pow(in[0], in2[0]);
+			if( x > 0 )
+				result = sqrtf(x);
 			else
-				out[0]= 0.0;
-		}
-		break;
-	case 11: /* Logarithm */
+				result = 0;
+		} break;
+	case 11: /* Power, x^y */
 		{
+			/* 
+			   FIXME button returns inaccurate float, even
+			   if it is set to an integer, so we have to round here.
+			   See Bug 17915. Should be replaced by 
+			   if ( x > 0 || y == (int)y ) once the GUI code is fixed.
+			*/
 			/* Don't want any imaginary numbers... */
-			if( in[0] > 0  && in2[0] > 0 )
-				out[0]= log(in[0]) / log(in2[0]);
+			if ( x > 0 ) {
+				result = powf(x, y);
+			} else {
+				float y_mod_1 = fmod(y,1);
+				if ( y_mod_1 > 0.999 || y_mod_1 < 0.001 )
+					result = powf(x, round(y));
+				else
+					result = 0;
+			}
+		} break;
+	case 12: /* Logarithm, logy(x) */
+		{
+			/* Don't want any imaginary numbers... */
+			if( x > 0  && y > 0 )
+				result = logf(x) / logf(y);
 			else
-				out[0]= 0.0;
-		}
-		break;
-	case 12: /* Minimum */
+				result = 0;
+		} break;
+	case 13: /* Minimum */
 		{
-			if( in[0] < in2[0] )
-				out[0]= in[0];
+			if( x < y)
+				result = x;
 			else
-				out[0]= in2[0];
-		}
-		break;
-	case 13: /* Maximum */
+				result = y;
+		} break;
+	case 14: /* Maximum */
 		{
-			if( in[0] > in2[0] )
-				out[0]= in[0];
+			if( x > y )
+				result = x;
 			else
-				out[0]= in2[0];
-		}
+				result = y;
+		} break;
+	case 15: /* Round, round(x)*/
+		result = (int)(x + 0.5f);
 		break;
-	case 14: /* Round */
-		{
-				out[0]= (int)(in[0] + 0.5f);
-		}
+	case 16: /* Less Than, x < y */
+		result = (x < y);
 		break;
-	case 15: /* Less Than */
-		{
-			if( in[0] < in2[0] )
-				out[0]= 1.0f;
-			else
-				out[0]= 0.0f;
-		}
+	case 17: /* Greater Than */
+		result = (x > y);
 		break;
-	case 16: /* Greater Than */
-		{
-			if( in[0] > in2[0] )
-				out[0]= 1.0f;
-			else
-				out[0]= 0.0f;
-		}
-		break;
 	}
+
+	*out = result;
 }
 
 static void node_composit_exec_math(void *data, bNode *node, bNodeStack **in, bNodeStack **out)
@@ -171,7 +178,7 @@
 		stackbuf=alloc_compbuf(cbuf->x, cbuf->y, CB_VAL, 1);
 	}
 	/* and if it doesn't exist use the second input since we 
- 	know that one of them must exist at this point*/
+	   know that one of them must exist at this point */
 	else  {
 		stackbuf=alloc_compbuf(cbuf2->x, cbuf2->y, CB_VAL, 1);
 	}
@@ -198,5 +205,3 @@
 	/* id          */	NULL
 };
 
-
-