Help with complex Raster Calculator expression?

[LitanMohanty]

I am writing an expression in raster calculator, the expression is like:

''1  /  1 + [ Exp * * - ( 10.358 + ( -0.213 * "debrisrast") + ( -0.226 * "frntalrast") + ( -11.172 * "massbrast")]''.

It showing an wright expression, but when i run the programme, it failed. so what might be the problem?

[DanPatterson_Retired]

Report the error message please and provide details on

• what help topics you examined ( ie Exp in spatial analyst   )
• the source and purpose of the equation and whether this is a verbatim copy from another source
• the nature/type of the raster,
• the coordinate system,
• the location of the source and destination files

[curtvprice · Accepted solution]

This is a valid python expression, but the brackets [ ] don't belong working with rasters.

The usage you are using for Exp tool is invalid, see the help link.

The following is a little more likely to work, though I can't vouch for the results:

1  / ( 1 + ( Exp( -1.0 * ( 10358 + ( -0.213 * "debrisrast") + 
    ( -0.226 * "frntalrast") + ( -11.172 * "massbrast") ))))

Exp  tool help : ArcGIS Help (10.2, 10.2.1, and 10.2.2)