[GRASS-dev] Re: r.series

[Glynn Clements]

Helena Mitasova wrote:

> it is almost working now. It is only the nan value that is still causing
> problems - you were right that the computation was correctly done for
> most of the area but because of the nan value the color table was not
> set correctly and the resulting map was plain white.
> I have an area in the series that is set to zero (ocean level) so those
> are the identical values where I am getting 0/0=nan. I can imagine other
> situations where this can happen so it would be good to change the nan
> result to null.

I've added the following change to CVS, which should catch NaNs:

--- lib/stats/c_reg.c~	2007-10-23 13:33:32.000000000 +0100
+++ lib/stats/c_reg.c	2007-10-23 19:34:29.000000000 +0100
@@ -70,6 +70,10 @@
 		G_set_d_null_value(result, 1);
 		break;
 	}
+
+	/* Check for NaN */
+	if (*result != *result)
+		G_set_d_null_value(result, 1);
 }
 
 void c_reg_m(DCELL *result, DCELL *values, int n)
@@ -153,6 +157,10 @@
 		G_set_d_null_value(result, 1);
 		break;
 	}
+
+	/* Check for NaN */
+	if (*result != *result)
+		G_set_d_null_value(result, 1);
 }
 
 void w_reg_m(DCELL *result, DCELL (*values)[2], int n)

I still have no idea if the actual calculation is correct, or even
*which* coefficient it's calculating.

-- 
Glynn Clements <glynn at gclements.plus.com>